crypto: ahash - check for shash type instead of not ahash type

Since the previous patch made crypto_shash_type visible to ahash.c,
change checks for '->cra_type != &crypto_ahash_type' to '->cra_type ==
&crypto_shash_type'.  This makes more sense and avoids having to
forward-declare crypto_ahash_type.  The result is still the same, since
the type is either shash or ahash here.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>