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/relocation.c b/fs/btrfs/relocation.c
index 7e7fd1b..6e530bb 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -4058,7 +4058,7 @@
 	       (unsigned long long)rc->block_group->flags);
 
 	btrfs_start_delalloc_inodes(fs_info->tree_root, 0);
-	btrfs_wait_ordered_extents(fs_info->tree_root, 0, 0);
+	btrfs_wait_ordered_extents(fs_info->tree_root, 0);
 
 	while (1) {
 		mutex_lock(&fs_info->cleaner_mutex);