CIFS: refactor crypto shash/sdesc allocation&free

shash and sdesc and always allocated and freed together.
* abstract this in new functions cifs_alloc_hash() and cifs_free_hash().
* make smb2/3 crypto allocation independent from each other.

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
CC: Stable <stable@vger.kernel.org>

fs/cifs/cifsproto.h

@@ -542,4 +542,9 @@ enum securityEnum cifs_select_sectype(struct TCP_Server_Info *,
 struct cifs_aio_ctx *cifs_aio_ctx_alloc(void);
 void cifs_aio_ctx_release(struct kref *refcount);
 int setup_aio_ctx_iter(struct cifs_aio_ctx *ctx, struct iov_iter *iter, int rw);
+
+int cifs_alloc_hash(const char *name, struct crypto_shash **shash,
+		    struct sdesc **sdesc);
+void cifs_free_hash(struct crypto_shash **shash, struct sdesc **sdesc);
+
 #endif			/* _CIFSPROTO_H */