crypto: hash - Add helpers to free spawns

This patch adds the helpers crypto_drop_ahash and crypto_drop_shash
so that these spawns can be dropped without ugly casts.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/internal/hash.h

@@ -69,6 +69,11 @@ int crypto_init_ahash_spawn(struct crypto_ahash_spawn *spawn,
 			    struct hash_alg_common *alg,
 			    struct crypto_instance *inst);
 
+static inline void crypto_drop_ahash(struct crypto_ahash_spawn *spawn)
+{
+	crypto_drop_spawn(&spawn->base);
+}
+
 struct hash_alg_common *ahash_attr_alg(struct rtattr *rta, u32 type, u32 mask);
 
 int crypto_register_shash(struct shash_alg *alg);
@@ -81,6 +86,11 @@ int crypto_init_shash_spawn(struct crypto_shash_spawn *spawn,
 			    struct shash_alg *alg,
 			    struct crypto_instance *inst);
 
+static inline void crypto_drop_shash(struct crypto_shash_spawn *spawn)
+{
+	crypto_drop_spawn(&spawn->base);
+}
+
 struct shash_alg *shash_attr_alg(struct rtattr *rta, u32 type, u32 mask);
 
 int shash_ahash_update(struct ahash_request *req, struct shash_desc *desc);