mac80211_hwsim: add regulatory testing options

This adds a module parameter for mac80211_hwsim regulatory testing.
This module parameter is designed specifically to help test the
different possible types of driver specific regulatory requests
and also helps to test world roaming, all without any hardware.

If you want to just simply test different alpha2s just use the userspace
regulatory request as this won't buy you anything new.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>