[][openwrt][mt7988][eth][Add HW version check for MT7988]

[Description]
Add hardware version check for MT7988.

If the hardware that we're using is MT7988 v2,
it can support dummy page feature, which is
going to be enabled by default.

If without this patch, MT7988 cannot enable dummy page.

[Release-log]
N/A


Change-Id: Ic34d16ccd117adf6f0be1444721d23e9a1b7fb25
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7420053
3 files changed