Polling for ath driver

[Nate Nielsen]

I've been working on polling for the FreeBSD ath wireless driver.

On slow CPU's polling helps prevent (by supressing certain interrupts)
livelock and increases throughput. This is true of Atheros cards on
Soekris and other embedded hardware.

Just thought I'd post something here in case anyone is interested in
helping with insight, code or testing. I've got a rough (and mostly
working) patch. There are some locking issues to contend with...

Cheers,
Nate