Base config compat check on MBETLS_VERSION_NUMBER

Any config with a version older than 3.0.0 or newer than
MBETLS_VERSION_NUMBER will be rejected.

This does mean that the current development version doesn'T accept *any*
value of MBETLS_CONFIG_VERSION, but this will be fixed when we bump the
version during our normal release process.

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 8aa88b0..80bbebd 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -25,13 +25,15 @@
  */
 
 /**
+ * \def MBEDTLS_CONFIG_VERSION
+ *
  * This is an optional version symbol that enables comatibility handling of
  * config files.
  *
  * It is equal to the #MBEDTLS_VERSION_NUMBER of the mbedtls version that
  * introduced the config format we want to be compatible with.
  */
-#define MBEDTLS_CONFIG_VERSION 0x03000000
+//#define MBEDTLS_CONFIG_VERSION 0x03000000
 
 /**
  * \name SECTION: System support