block: use lockdep_assert_held for queue locking

Instead of an ugly open coded variant.

Cc: axboe@kernel.dk
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 5eed6a7..f2ddb94 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -1218,7 +1218,7 @@
 	struct bio_list bl;
 	struct bio *bio;
 
-	WARN_ON_ONCE(!queue_is_locked(q));
+	queue_lockdep_assert_held(q);
 
 	bio_list_init(&bl);