Note that ECC key derivation is not using drivers yet, as we don't have driver support for
cooked key derivation acceleration, see
https://github.com/Mbed-TLS/mbedtls/pull/5451 and follow-ups.
So, we still need MBEDTLS_ECP_C enabled at least for this, and probably
in several other places for now.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>