crypto: doc - document correct return value for request allocation

Signed-off-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/hash.h b/include/crypto/hash.h
index 1969f14..2660588 100644
--- a/include/crypto/hash.h
+++ b/include/crypto/hash.h
@@ -547,8 +547,7 @@
  * the allocation, the provided ahash handle
  * is registered in the request data structure.
  *
- * Return: allocated request handle in case of success; IS_ERR() is true in case
- *	   of an error, PTR_ERR() returns the error code.
+ * Return: allocated request handle in case of success, or NULL if out of memory
  */
 static inline struct ahash_request *ahash_request_alloc(
 	struct crypto_ahash *tfm, gfp_t gfp)