crypto: hash - Add crypto_ahash_has_setkey

This patch adds a way for ahash users to determine whether a key
is required by a crypto_ahash transform.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/ahash.c b/crypto/ahash.c
index 9c1dc8d..d19b523 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -451,6 +451,7 @@
 	struct ahash_alg *alg = crypto_ahash_alg(hash);
 
 	hash->setkey = ahash_nosetkey;
+	hash->has_setkey = false;
 	hash->export = ahash_no_export;
 	hash->import = ahash_no_import;
 
@@ -463,8 +464,10 @@
 	hash->finup = alg->finup ?: ahash_def_finup;
 	hash->digest = alg->digest;
 
-	if (alg->setkey)
+	if (alg->setkey) {
 		hash->setkey = alg->setkey;
+		hash->has_setkey = true;
+	}
 	if (alg->export)
 		hash->export = alg->export;
 	if (alg->import)