[][kernel][common][hnat][Refactor HNAT flow to prevent entry modification racing]

[Description]
Refactor HNAT flow to prevent entry modification racing.

[Release-log]
N/A


Change-Id: Ia1541424ed0fc1f744f1bd5a0efc64e9c74cd0bf
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/9246920
3 files changed