drbd: use list_move_tail instead of list_del/list_add_tail

Using list_move_tail() instead of list_del() + list_add_tail().

spatch with a semantic match is used to found this problem.
(http://coccinelle.lip6.fr/)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_worker.c

@@ -134,8 +134,7 @@ static void drbd_endio_write_sec_final(struct drbd_peer_request *peer_req) __rel
 
 	spin_lock_irqsave(&mdev->tconn->req_lock, flags);
 	mdev->writ_cnt += peer_req->i.size >> 9;
-	list_del(&peer_req->w.list); /* has been on active_ee or sync_ee */
-	list_add_tail(&peer_req->w.list, &mdev->done_ee);
+	list_move_tail(&peer_req->w.list, &mdev->done_ee);
 
 	/*
 	 * Do not remove from the write_requests tree here: we did not send the