drivers/block/loop.c: emit uevent on auto release

The loopback driver failed to emit the change uevent when auto releasing
the device.  Fixed lo_release() to pass the bdev to loop_clr_fd() so it
can emit the event.
Signed-off-by: NPhillip Susi <psusi@cfl.rr.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ayan George <ayan@ayan.net>
Signed-off-by: NAndrew Morton <akpm@google.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

drivers/block/loop.c

@@ -1583,7 +1583,7 @@ static int lo_release(struct gendisk *disk, fmode_t mode)
 		 * In autoclear mode, stop the loop thread
 		 * and remove configuration after last close.
 		 */
-		err = loop_clr_fd(lo, NULL);
+		err = loop_clr_fd(lo, lo->lo_device);
 		if (!err)
 			goto out_unlocked;
 	} else {