spectral scan now works on ar93xx and later chips

[Adrian Chadd]

Hiya,

I've brought in the spectral scan code for the ar93xx and later chips.
It wasn't that much work.

To use it:

* add ATH_ENABLE_RADIOTAP_VENDOR_EXT, ATH_DIAGAPI to your kernel
config and rebuild. I'd love to have this radiotap vendor data be in
by default by tcpdump doesn't decode radiotap vendor data correctly
yet and doesn't skip over it :(

* compile athspectral (tools/ath/ath); to see it just 'athspectral
enable_on_reset 1'
* sysctl dev.ath.0.monpass=0xffff (so it passes up all PHY error
frames up to the stack via radiotap - spectral scan data and radar
reports are PHY errors with a payload);
* ifconfig wlanX create wlandev ath0 ssid foo123 up (so it stays up
and continuously scans, but hopefully never finds the ssid 'foo123');
* clone github.com/erikarn/ath_radar_stuff, build, and run 'fft_eval
ar9280 if wlanX' (where 'wlanX' is the wlan interface);
* watch the pretty data



-adrian