[][openwrt][mt7988][hnat][Add extensions for 3-WED/3-WDMA offload]

[Description]
Add extensions to support 3-WED/3-WDMA wifi offload.

If without this patch, WiFi offload is not able to run
3-WED/3-WDMA scenario.

[Release-log]
N/A


Change-Id: I184610e5327a1135366a3524610cd293aa72e9fe
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7824471
2 files changed