Btrfs: cleanup of function where fixup_low_keys() is called

If argument 'trans' is unnecessary in the function where
fixup_low_keys() is called, 'trans' is deleted.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index 502c215..47cab8d 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -442,8 +442,7 @@
 		start = btrfs_item_ptr_offset(leaf, path->slots[0]);
 		memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
 			item_len - (ptr + sub_item_len - start));
-		btrfs_truncate_item(trans, root, path,
-				    item_len - sub_item_len, 1);
+		btrfs_truncate_item(root, path, item_len - sub_item_len, 1);
 	}
 	return ret;
 }