Add `MBEDTLS_RSA_NO_CRT` to options unaffected by `config.pl full`

The effect of `config.pl full` on 'negative' options such as
`NO_PLATFORM_ENTROPY` is usually inverted, but `MBEDTLS_RSA_NO_CRT` was not
included in the list of such options. This commit adds it.
diff --git a/scripts/config.pl b/scripts/config.pl
index 2757f17..e2760b1 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -17,7 +17,7 @@
 #
 # Full usage description provided below.
 #
-# Things that shouldn't be enabled with "full".
+# The following options are disabled instead of enabled with "full".
 #
 #   MBEDTLS_TEST_NULL_ENTROPY
 #   MBEDTLS_DEPRECATED_REMOVED
@@ -30,6 +30,7 @@
 #   MBEDTLS_NO_PLATFORM_ENTROPY
 #   MBEDTLS_REMOVE_ARC4_CIPHERSUITES
 #   MBEDTLS_SSL_HW_RECORD_ACCEL
+#   MBEDTLS_RSA_NO_CRT
 #   MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3
 #   MBEDTLS_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION
 #       - this could be enabled if the respective tests were adapted
@@ -85,6 +86,7 @@
 MBEDTLS_ECP_DP_M511_ENABLED
 MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES
 MBEDTLS_NO_PLATFORM_ENTROPY
+MBEDTLS_RSA_NO_CRT
 MBEDTLS_REMOVE_ARC4_CIPHERSUITES
 MBEDTLS_SSL_HW_RECORD_ACCEL
 MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3