Rename mbedtls_ssl_session minor_ver to tls_version

Store the TLS version instead of minor version number in tls_version.

Note: struct member size changed from unsigned char to uint16_t
Due to standard structure padding, the structure size does not change
unless alignment is 1-byte (instead of 2-byte or more)

Note: existing application use which accesses the struct member
(using MBEDTLS_PRIVATE) is compatible on little-endian platforms,
but not compatible on big-endian platforms.  The enum values for
the lower byte of MBEDTLS_SSL_VERSION_TLS1_2 and of
MBEDTLS_SSL_VERSION_TLS1_3 matches MBEDTLS_SSL_MINOR_VERSION_3 and
MBEDTLS_SSL_MINOR_VERSION_4, respectively.

Note: care has been taken to preserve serialized session format,
which uses only the lower byte of the TLS version.

Signed-off-by: Glenn Strauss <gstrauss@gluelogic.com>
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 0ba501d..da42cd9 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -1634,7 +1634,7 @@
 #if defined(MBEDTLS_HAVE_TIME)
     session->start = mbedtls_time( NULL ) - 42;
 #endif
-    session->minor_ver = MBEDTLS_SSL_MINOR_VERSION_3;
+    session->tls_version = MBEDTLS_SSL_VERSION_TLS1_2;
     session->ciphersuite = 0xabcd;
     session->compression = 1;
     session->id_len = sizeof( session->id );
@@ -4585,7 +4585,7 @@
 #if defined(MBEDTLS_HAVE_TIME)
     TEST_ASSERT( original.start == restored.start );
 #endif
-    TEST_ASSERT( original.minor_ver == restored.minor_ver );
+    TEST_ASSERT( original.tls_version == restored.tls_version );
     TEST_ASSERT( original.ciphersuite == restored.ciphersuite );
     TEST_ASSERT( original.compression == restored.compression );
     TEST_ASSERT( original.id_len == restored.id_len );