wifi: add support for 802.11ax High-Efficiency modes
Add support for new High-Efficiency Wireless (HEW) modes in 802.11ax
Allow new htmodes:
- HE20
- HE40
- HE80
- HE160
OpenWrt References:
- https://github.com/openwrt/openwrt/blob/1796812e1d1864df261d06ff6535718d3ae1a6c5/package/network/services/hostapd/files/hostapd.sh#L1170
- https://patchwork.ozlabs.org/project/openwrt/patch/20210428110540.354764-1-mail@david-bauer.net/
cc: @jhoracek