crypto: aead - Fix corner case in crypto_lookup_aead

When the user explicitly states that they don't care whether the
algorithm has been tested (type = CRYPTO_ALG_TESTED and mask = 0),
there is a corner case where we may erroneously return ENOENT.

This patch fixes it by correcting the logic in the test.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>