[][Update dscp for qos by keepalive]

Add Update dscp for qos by keepalive
Some programs will change dscp or other field in skb runtime,
so we need use keepalive packet to trigger clear entry.
Then hnat learn the complete new information.
And we also need to clear the cache to maintain consistency.


Change-Id: Ide74c3ff63e6d4ac3ac529fe94790fc7b8127ce1
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5140635
1 file changed