[][kernel][mt7988][eth][remove XFRM offload related code]

[Description]
Remove XFRM offload related code since they should not be bound with
kernel ethernet driver and most of these code are in development.
Instead of providing XFRM offload feature inside ethernet driver, we
implement another package to support XFRM offload feature with EIP197.

[Release-log]
N/A

Change-Id: I883d5bf7faf175f843569f420dbc2d065addd502
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7826442
4 files changed