Tidy up some of the configuration options:

* Add AH_SUPPORT_AR9300
* disable Hornet (AR9330), Wasp (AR9340), Scorpion (AR95xx) SoC support;
  there's no point in supporting that until the SoC support is there.
  (Although Hornet support is almost ready for this..)
* Remove mavrick_sta, it's no longer needed