confile: cleanup clr_config_net_flags()

src/lxc/confile.c

@@ -5223,7 +5223,7 @@ static int clr_config_net_flags(const char *key, struct lxc_conf *lxc_conf,
 	struct lxc_netdev *netdev = data;
 
 	if (!netdev)
-		return -1;
+		return ret_errno(EINVAL);
 
 	netdev->flags = 0;