PSA: Reject curves that are not enabled in the PSA configuration
PSA: Reject curves that are not enabled in the PSA configuration

If an elliptic curve was enabled in the Mbed TLS classic API (#define
MBEDTLS_ECP_DP_xxx), but not enabled in the PSA configuration (#define
PSA_WANT_ECC_xxx), it would still work if you tried to use it through
PSA.

This is generally benign, but could be a security issue if you want to
disable a curve in PSA for some security reason (such as a known bug
in its implementation, which may not matter in the classic API if Mbed
TLS is running in a secure enclave and is only reachable from
untrusted callers through the PSA API). More urgently, this broke
test_suite_psa_crypto_not_supported.generated.

So if a curve is not enabled in the PSA configuration, ensure that
it's treated as unsupported through the PSA software implementation.

Signed-off-by: Gilles Peskine <f805f64266d288fc5467baa7be6cd0ff366f477b@arm.com>

ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,NXPmicro/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls