dm bufio: use list_move

Use list_move() instead of list_del() + list_add().

spatch with a semantic match was used to find this.
(http://coccinelle.lip6.fr/)
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

drivers/md/dm-bufio.c

@@ -441,8 +441,7 @@ static void __relink_lru(struct dm_buffer *b, int dirty)
 	c->n_buffers[b->list_mode]--;
 	c->n_buffers[dirty]++;
 	b->list_mode = dirty;
-	list_del(&b->lru_list);
-	list_add(&b->lru_list, &c->lru[dirty]);
+	list_move(&b->lru_list, &c->lru[dirty]);
 }
 
 /*----------------------------------------------------------------