Btrfs: delete unused parameter to btrfs_read_root_item()

Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 84c4fa5..a03a966 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1481,7 +1481,7 @@
 	if (ret == 0) {
 		l = path->nodes[0];
 		slot = path->slots[0];
-		btrfs_read_root_item(tree_root, l, slot, &root->root_item);
+		btrfs_read_root_item(l, slot, &root->root_item);
 		memcpy(&root->root_key, location, sizeof(*location));
 	}
 	btrfs_free_path(path);