rbd: don't mess with a page vector in rbd_notify_op_lock()

rbd_notify_op_lock() isn't interested in a notify reply. Instead of
accepting that page vector just to free it, have watch-notify code take
care of it.

Signed-off-by: Ilya Dryomov <[e-mail]>
Reviewed-by: Jason Dillaman <[e-mail]>

drivers/block/rbd.c

···
 static void rbd_notify_op_lock(struct rbd_device *rbd_dev,
 			       enum rbd_notify_op notify_op)
 {
-	struct page **reply_pages;
-	size_t reply_len;
-
-	__rbd_notify_op_lock(rbd_dev, notify_op, &reply_pages, &reply_len);
-	ceph_release_page_vector(reply_pages, calc_pages_for(0, reply_len));
+	__rbd_notify_op_lock(rbd_dev, notify_op, NULL, NULL);
 }
 
 static void rbd_notify_acquired_lock(struct work_struct *work)