Btrfs: kill obsolete arguments in btrfs_wait_ordered_extents

nocow_only is now an obsolete argument.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 903ab2d..5aa3b81 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -852,7 +852,7 @@
 		return 0;
 	}
 
-	btrfs_wait_ordered_extents(root, 0, 0);
+	btrfs_wait_ordered_extents(root, 0);
 
 	trans = btrfs_join_transaction_freeze(root);
 	if (IS_ERR(trans)) {