crypto: hash - Make setkey optional

Since most cryptographic hash algorithms have no keys, this patch
makes the setkey function optional for ahash and shash.

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

crypto/ahash.c

@@ -162,6 +162,12 @@ static int ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
 	return ahash->setkey(tfm, key, keylen);
 }
 
+static int ahash_nosetkey(struct crypto_ahash *tfm, const u8 *key,
+			  unsigned int keylen)
+{
+	return -ENOSYS;
+}
+
 int crypto_ahash_import(struct ahash_request *req, const u8 *in)
 {
 	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
@@ -194,7 +200,7 @@ static int crypto_init_ahash_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 	crt->update = alg->update;
 	crt->final  = alg->final;
 	crt->digest = alg->digest;
-	crt->setkey = ahash_setkey;
+	crt->setkey = alg->setkey ? ahash_setkey : ahash_nosetkey;
 	crt->digestsize = alg->digestsize;
 
 	return 0;