Features are generated by scripts/generate_features.pl which will reside
in the MbedTLS repository, while MBEDTLS_AES_C now resides in tf-psa-crypto.
Picking `MBEDTLS_TIMING_C` feature ensures the original test's requirements
are satisfied.
Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>