wifi: add 802.11ac 160 MHz wide channel
Follow-up of turris/foris-controller/foris-controller#106 (closed)
Add 160 MHz wide channel (VHT160) to dropdown menu. Note that not every 802.11ac
certified wifi card is capable of using VHT160 and dropdown menu should only show channel widths that are present in data from backend.
In current state, this mode is ignored and shown as Disabled