Update spelling "mbed TLS" to "Mbed TLS"

The official spelling of the trade mark changed from all-lowercase "mbed"
to normal proper noun capitalization "Mbed" a few years ago. We've been
using the new spelling in new text but still have the old spelling in a
lot of text. This commit updates most occurrences of "mbed TLS":

```
sed -i -e 's/mbed TLS/Mbed TLS/g' $(git ls-files ':!ChangeLog' ':!tests/data_files/**' ':!tests/suites/*.data' ':!programs/x509/*' ':!configs/tfm*')
```

Justification for the omissions:

* `ChangeLog`: historical text.
* `test/data_files/**`, `tests/suites/*.data`, `programs/x509/*`: many
  occurrences are significant names in certificates and such. Changing
  the spelling would invalidate many signatures and tests.
* `configs/tfm*`: this is an imported file. We'll follow the upstream
  updates.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/compat.sh b/tests/compat.sh
index 9529975..ba8465b 100755
--- a/tests/compat.sh
+++ b/tests/compat.sh
@@ -276,7 +276,7 @@
 {
     if [ "X" != "X$FILTER" -o "X" != "X$EXCLUDE" ];
     then
-        # Ciphersuite for mbed TLS
+        # Ciphersuite for Mbed TLS
         M_CIPHERS=$( filter "$M_CIPHERS" )
 
         # Ciphersuite for OpenSSL
@@ -286,7 +286,7 @@
         G_CIPHERS=$( filter "$G_CIPHERS" )
     fi
 
-    # For GnuTLS client -> mbed TLS server,
+    # For GnuTLS client -> Mbed TLS server,
     # we need to force IPv4 by connecting to 127.0.0.1 but then auth fails
     if is_dtls "$MODE" && [ "X$VERIFY" = "XYES" ]; then
         G_CIPHERS=""
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 4ed1949..19c9cc5 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -125,7 +125,7 @@
 
 pre_check_environment () {
     if [ -d library -a -d include -a -d tests ]; then :; else
-        echo "Must be run from mbed TLS root" >&2
+        echo "Must be run from Mbed TLS root" >&2
         exit 1
     fi
 }
diff --git a/tests/scripts/basic-build-test.sh b/tests/scripts/basic-build-test.sh
index abc4a2f..196ce45 100755
--- a/tests/scripts/basic-build-test.sh
+++ b/tests/scripts/basic-build-test.sh
@@ -43,7 +43,7 @@
 set -eu
 
 if [ -d library -a -d include -a -d tests ]; then :; else
-    echo "Must be run from mbed TLS root" >&2
+    echo "Must be run from Mbed TLS root" >&2
     exit 1
 fi
 
diff --git a/tests/scripts/check-doxy-blocks.pl b/tests/scripts/check-doxy-blocks.pl
index 3ed7069..dd95530 100755
--- a/tests/scripts/check-doxy-blocks.pl
+++ b/tests/scripts/check-doxy-blocks.pl
@@ -68,7 +68,7 @@
 # Check that the script is being run from the project's root directory.
 for my $dir (@directories) {
     if (! -d $dir) {
-        die "This script must be run from the mbed TLS root directory";
+        die "This script must be run from the Mbed TLS root directory";
     } else {
         check_dir($dir)
     }
diff --git a/tests/scripts/check-generated-files.sh b/tests/scripts/check-generated-files.sh
index f8a2449..ac0a08d 100755
--- a/tests/scripts/check-generated-files.sh
+++ b/tests/scripts/check-generated-files.sh
@@ -34,7 +34,7 @@
 fi
 
 if [ -d library -a -d include -a -d tests ]; then :; else
-    echo "Must be run from mbed TLS root" >&2
+    echo "Must be run from Mbed TLS root" >&2
     exit 1
 fi
 
diff --git a/tests/scripts/doxygen.sh b/tests/scripts/doxygen.sh
index 2bc8dc9..cb87829 100755
--- a/tests/scripts/doxygen.sh
+++ b/tests/scripts/doxygen.sh
@@ -21,7 +21,7 @@
 set -eu
 
 if [ -d library -a -d include -a -d tests ]; then :; else
-    echo "Must be run from mbed TLS root" >&2
+    echo "Must be run from Mbed TLS root" >&2
     exit 1
 fi
 
diff --git a/tests/scripts/generate-afl-tests.sh b/tests/scripts/generate-afl-tests.sh
index a640b56..a51fbc9 100755
--- a/tests/scripts/generate-afl-tests.sh
+++ b/tests/scripts/generate-afl-tests.sh
@@ -41,7 +41,7 @@
 if [ -d ../library -a -d ../include -a -d ../tests -a $THIS_DIR == "tests" ];
 then :;
 else
-    echo " [!] Must be run from mbed TLS tests directory" >&2
+    echo " [!] Must be run from Mbed TLS tests directory" >&2
     exit 1
 fi
 
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index a3103d9..b134061 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -489,7 +489,7 @@
      * MBEDTLS_ECP_WINDOW_SIZE, as well as implementation details that may
      * change in the future. A factor 2 is a minimum safety margin.
      *
-     * For reference, with mbed TLS 2.4 and default settings, for P-256:
+     * For reference, with Mbed TLS 2.4 and default settings, for P-256:
      * - Random point mult:     ~3250M
      * - Cold base point mult:  ~3300M
      * - Hot base point mult:   ~1100M
diff --git a/tests/suites/test_suite_version.function b/tests/suites/test_suite_version.function
index 981f8ab..eeae512 100644
--- a/tests/suites/test_suite_version.function
+++ b/tests/suites/test_suite_version.function
@@ -20,7 +20,7 @@
     mbedtls_snprintf(build_str, 100, "%d.%d.%d", MBEDTLS_VERSION_MAJOR,
                      MBEDTLS_VERSION_MINOR, MBEDTLS_VERSION_PATCH);
 
-    mbedtls_snprintf(build_str_full, 100, "mbed TLS %d.%d.%d", MBEDTLS_VERSION_MAJOR,
+    mbedtls_snprintf(build_str_full, 100, "Mbed TLS %d.%d.%d", MBEDTLS_VERSION_MAJOR,
                      MBEDTLS_VERSION_MINOR, MBEDTLS_VERSION_PATCH);
 
     build_int = MBEDTLS_VERSION_MAJOR << 24 |
@@ -56,7 +56,7 @@
                      (get_int >> 24) & 0xFF,
                      (get_int >> 16) & 0xFF,
                      (get_int >> 8) & 0xFF);
-    mbedtls_snprintf(build_str_full, 100, "mbed TLS %s", version_str);
+    mbedtls_snprintf(build_str_full, 100, "Mbed TLS %s", version_str);
 
     TEST_ASSERT(strcmp(build_str, version_str) == 0);
     TEST_ASSERT(strcmp(build_str_full, get_str_full) == 0);
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index 09a9d12..6e32792 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -564,7 +564,7 @@
     /*
      * See comments on ecp_test_vect_restart() for op count precision.
      *
-     * For reference, with mbed TLS 2.6 and default settings:
+     * For reference, with Mbed TLS 2.6 and default settings:
      * - ecdsa_verify() for P-256:  ~  6700
      * - ecdsa_verify() for P-384:  ~ 18800
      * - x509_verify() for server5 -> test-ca2:             ~ 18800