[BLOCK] elevator switch fixes/cleanup

- 100msec sleep is a little excessive, lots of requests can complete
  in that timeframe. Use 10msec instead.
- Rename QUEUE_FLAG_BYPASS to QUEUE_FLAG_ELVSWITCH to indicate what
  is going on.

Signed-off-by: Jens Axboe <axboe@suse.de>
diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index f7c9931..fc12d01 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -1940,7 +1940,7 @@
 	if (rl->count[rw] >= queue_congestion_on_threshold(q))
 		set_queue_congested(q, rw);
 
-	priv = !test_bit(QUEUE_FLAG_BYPASS, &q->queue_flags);
+	priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
 	if (priv)
 		rl->elvpriv++;