crypto: hmac - Fix incorrect error value when creating instance

If shash_alloc_instance() fails, we return the wrong error value.
This patch fixes it.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/hmac.c

@@ -195,6 +195,7 @@ static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
 		goto out_put_alg;
 
 	inst = shash_alloc_instance("hmac", alg);
+	err = PTR_ERR(inst);
 	if (IS_ERR(inst))
 		goto out_put_alg;