blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()

There's a single user of this function, dm, and dm just wants
to check if IO is inflight, not that it's just allocated.

This fixes a hang with srp/002 in blktests with dm, where it tries
to suspend but waits for inflight IO to finish first. As it checks
for just allocated requests, this fails.

Tested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/dm.c

@@ -663,7 +663,7 @@ static bool md_in_flight_bios(struct mapped_device *md)
 static bool md_in_flight(struct mapped_device *md)
 {
 	if (queue_is_mq(md->queue))
-		return blk_mq_queue_busy(md->queue);
+		return blk_mq_queue_inflight(md->queue);
 	else
 		return md_in_flight_bios(md);
 }