[][MAC80211][WiFi6][mt76][Add support for lpi and duplicate mode]

[Description]
Add support for lpi and duplicate mode.
1. lpi_enable: lpi fw cmd and set psd flag to fw by the country setting.
2. txpower_dup: Add bandwidth duplicate mode for 6g band and change power value of beacon.
3. mgmt_pwr_enhence: Add mgmt frame power enhencement by fix 6g band bandwidth
4. support runtime change sku table by specify sku index (default will find the first match country).
5. Add parsing negative txpower stored unsigned in dts.

[Release-log]
N/A

Change-Id: I4e87639f923e4068c2a811ea28dc1a812e694c07
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8434863
2 files changed