[][Add sanity check to bypass invalid packet]

[Description]
Add sanity check to avoid processing invalid packet for NF_HNAT.

[Release-log]
N/A

Change-Id: I5330205d61f31b761f2c9c0f76258cabceaccd31
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4627575
1 file changed