bfq: use bfq_bic_lookup in bfq_limit_depth

No need to create a new I/O context if there is none present yet in
->limit_depth.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211126115817.2087431-5-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/bfq-iosched.c

@@ -663,7 +663,7 @@ static bool bfqq_request_over_limit(struct bfq_queue *bfqq, int limit)
 static void bfq_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
 {
 	struct bfq_data *bfqd = data->q->elevator->elevator_data;
-	struct bfq_io_cq *bic = icq_to_bic(blk_mq_sched_get_icq(data->q));
+	struct bfq_io_cq *bic = bfq_bic_lookup(data->q);
 	struct bfq_queue *bfqq = bic ? bic_to_bfqq(bic, op_is_sync(op)) : NULL;
 	int depth;
 	unsigned limit = data->q->nr_requests;