[][Kernel][mt7988][common][Add USB NET Driver Support]

[Description]
Add configurations to enable USB NET driver support.

If without this patch, USB Ethernet dongle cannot work.

[Release-log]
N/A


Change-Id: I2ec9935fd01b052013b1c6304ac34e37ecc30cd1
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7022819
3 files changed