cfg80211: add support for custom firmware regulatory solutions

This adds API to cfg80211 to allow wireless drivers to inform
us if their firmware can handle regulatory considerations *and*
they cannot map these regulatory domains to an ISO / IEC 3166
alpha2. In these cases we skip the first regulatory hint instead
of expecting the driver to build their own regulatory structure,
providing us with an alpha2, or using the reg_notifier().

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>