[][MAC80211][WiFi6][mt76][Disable RegDB when enable single sku]

[Description]
Refactor init txpower flow, disable RegDB when enable single sku.
And add e2p and RegDB maximum txpower in debugfs.

[Release-log]

Change-Id: If137b701c8f17cd894d6e5ec2ef19cdb0dfc96a4
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7875956
1 file changed