btrfs: Simplify btrfs_insert_root

btrfs_insert_root is just a wrapper for btrfs_insert_item. Just return
the error directly.
Signed-off-by: NJeff Mahoney <jeffm@suse.com>

fs/btrfs/root-tree.c

@@ -116,13 +116,10 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 	return ret;
 }
 
-int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
-		      *root, struct btrfs_key *key, struct btrfs_root_item
-		      *item)
+int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		      struct btrfs_key *key, struct btrfs_root_item *item)
 {
-	int ret;
-	ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
-	return ret;
+	return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 }
 
 /*