bfq: Remove useless code in bfq_lookup_next_entity

It is no need to judge entity is null or not here,
directly return entity is ok, so remove it.
Signed-off-by: NGuoYong Zheng <zhenggy@chinatelecom.cn>
Link: https://lore.kernel.org/r/1655461684-19075-1-git-send-email-zhenggy@chinatelecom.cnSigned-off-by: NJens Axboe <axboe@kernel.dk>

block/bfq-wf2q.c

@@ -1472,9 +1472,6 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
 			break;
 	}
 
-	if (!entity)
-		return NULL;
-
 	return entity;
 }