veth: disable gro on receive path only

Still keep it enabled in veth tx path.

For veth environment only.
diff --git a/net/core/gro.c b/net/core/gro.c
index 4bac7ea..6301233 100644
--- a/net/core/gro.c
+++ b/net/core/gro.c
@@ -489,7 +489,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 	int same_flow;
 	int grow;
 
-	if (netif_elide_gro(skb->dev))
+	if (1) //netif_elide_gro(skb->dev))
 		goto normal;
 
 	gro_list_prepare(&gro_list->list, skb);