[][Kernel][hnat][Fix hook drop packet]

[Description]
Fix hook drop normal packet
In some cases, the packet match the to the logic
of eth->wlan of the legacy chip(mt7621).
After failing to find the interface,
it will be discarded by the hnat function.
Here packets should be handed over to the kernel

[Release-log]
N/A


Change-Id: Idca4c6e899e743c89fbcb562f2695a77b02a98af
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7265953
1 file changed