Support for Android for mac80211 / cfg80211 802.11 drivers

We get poked every now and then for Android support for mac80211 or
cfg80211 drivers. Since the questions is quite common I figured It'd
be good to document what needs to get done for this. Android folks,
you listening?

http://wireless.kernel.org/en/developers/Documentation/Android

If you already have worked on this or are going to please feel free to
update the wiki so no one else re-invents the wheel.

Thanks,

 Luis