Drivers may need more information than just who set the last regulatory domain,
as such lets just pass the last regulatory_request receipt. To do this we need
to move out to headers struct regulatory_request, and enum environment_cap. While
at it lets add documentation for enum environment_cap.
Signed-off-by: NLuis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>