psa_aead_encrypt_setup() and psa_aead_decrypt_setup() were returning
PSA_ERROR_INVALID_ARGUMENT, while the same failed checks were producing
PSA_ERROR_NOT_SUPPORTED if they happened in psa_aead_encrypt() or
psa_aead_decrypt().
The PSA Crypto API 1.1 spec will specify PSA_ERROR_INVALID_ARGUMENT
in the case that the supplied algorithm is not an AEAD one.
Also move these shared checks to a helper function, to reduce code
duplication and ensure that the functions remain in sync.
Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>