crypto: ahash - unexport crypto_ahash_type

Now that all the templates that need ahash spawns have been converted to
use crypto_grab_ahash() rather than look up the algorithm directly,
crypto_ahash_type is no longer used outside of ahash.c.  Make it static.

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

include/crypto/internal/hash.h

@@ -57,8 +57,6 @@ struct crypto_shash_spawn {
 	struct crypto_spawn base;
 };
 
-extern const struct crypto_type crypto_ahash_type;
-
 int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err);
 int crypto_hash_walk_first(struct ahash_request *req,
 			   struct crypto_hash_walk *walk);