modules: mbedtls: Add Kconfig entry for MBEDTLS_MD and MBEDTLS_CIPHER

Due to new checks in mbedTLS config sanitizer, TLS option can no longer
be left enabled, when TLS is not used. OpenThread needs MBEDTLS_MD_C
and MBEDTLS_CIPHER_C even without TLS being used, so we need an option
to enable them manually.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>