please review - channel representation proposal and example

hi!

I've been working on a proposal to rototill how we represent channels
in net80211 stack and drivers. My hope is this work will lead us
towards a single entry per channel (with options) and unlocking 11ax,
320MHz wide stuff, OFDM-A configuration, 6GHz, 60GHz and other
configurations without a further massive explosion of channel entries.

The proposal is here:

https://wiki.freebsd.org/AdrianChadd/Net80211ChannelRepresentation2026

And an example exploratory diff that converts some stuff away from
direct manipulation and into macros that hopefully make things easier
to further refactor:

https://reviews.freebsd.org/D48172

I'd really like some feedback here.

It's a lot of work that can break things in subtle ways, so I'm trying
very hard to figure out a path forward that incrementally cleans
things up in a more useful direction that we can all sort of agree
upon.

Thanks!


-adrian