btrfs: Remove unnecessary variants in relocation.c

These arguments are not used in functions, remove them for cleanup
and make kernel stack happy.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index f5021fc..91f44c9 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1301,7 +1301,7 @@
 	 */
 	btrfs_set_skip_qgroup(trans, objectid);
 
-	btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
+	btrfs_reloc_pre_snapshot(pending, &to_reserve);
 
 	if (to_reserve > 0) {
 		pending->error = btrfs_block_rsv_add(root,