dm: fix second blk_delay_queue() parameter to be in msec units not jiffies

Commit d548b34b062 ("dm: reduce the queue delay used in dm_request_fn
from 100ms to 10ms") always intended the value to be 10 msecs -- it
just expressed it in jiffies because earlier commit 7eaceaccab ("block:
remove per-queue plugging") did.

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Fixes: d548b34b062 ("dm: reduce the queue delay used in dm_request_fn from 100ms to 10ms")
Cc: stable@vger.kernel.org # 4.1+ -- stable@ backports must be applied to drivers/md/dm.c

drivers/md/dm-rq.c

@@ -785,7 +785,7 @@ static void dm_old_request_fn(struct request_queue *q)
 		     md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
 		     md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
 		    (ti->type->busy && ti->type->busy(ti))) {
-			blk_delay_queue(q, HZ / 100);
+			blk_delay_queue(q, 10);
 			return;
 		}