[][Update set_iif judgement for NF_HNAT]

[Description]
Add set_iif judgement for NF_HNAT driver.
Making it more precise can prevent Linux skb reuse problem.

[Release-log]
N/A

Change-Id: I189bcdefaadafdfa556853f7352ee9d4971d7f3b
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4691350
1 file changed