Add error condition for bad user configurations

This commit adds an error condition for bad user configurations
and updates the number of SSL module errors in error.h.

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/error.c b/library/error.c
index 22c7b16..7e7f788 100644
--- a/library/error.c
+++ b/library/error.c
@@ -522,6 +522,8 @@
             return( "SSL - An operation failed due to an unexpected version or configuration" );
         case -(MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS):
             return( "SSL - A cryptographic operation is in progress. Try again later" );
+        case -(MBEDTLS_ERR_SSL_BAD_CONFIG):
+            return( "SSL - Invalid value in SSL config" );
 #endif /* MBEDTLS_SSL_TLS_C */
 
 #if defined(MBEDTLS_X509_USE_C) || defined(MBEDTLS_X509_CREATE_C)