refactor(mbedtls): avoid including MBEDTLS_CONFIG_FILE

refactor(mbedtls): avoid including MBEDTLS_CONFIG_FILE

Currently we include MBEDTLS_CONFIG_FILE directly and if a custom
config file is used it will included.

However from mbedtls-3.x onwards it discourages usage of
MBEDTLS_CONFIG_FILE include directly, so to resolve this and keep 2.28
compatibility include version.h which would include the custom config
file if present and also would expose us with mbedtls-major-version
number which could be used for selecting features and functions for
mbedtls 2.28 or 3.3

Change-Id: I029992311be2a38b588ebbb350875b03ea29acdb
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>