[athani] Add a simple tool to list and control ANI parameters.
This is a WIP tool I'm using to figure out why ANI is weirdly busted in my
home FreeBSD AP/STA setup. Although athstats (mostly) gets the ANI statistics
correct, ANI is making the radio deaf it doesn't recover without being disabled.
It's very WIP.
- Carambola 2, (AR9331), AP/STA mode.