Some negative tests involving unsupported mechanisms are executed, because
they're testing what happens if the mechanism is unsupported. Refine the
ignore list for `test_suite_psa_crypto_generate_key.generated` and
`test_suite_psa_crypto_op_fail.generated` accordingly.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>