cfg80211: process regulatory DFS region for countries

The wireless-regdb now has support for mapping a country to
one DFS region. CRDA sends this to us now so process it
so we can provide that hint to drivers. This will later be
used by code for processing DFS in a way that meets the
criteria for the DFS region the country belongs to.

Signed-off-by: Luis R. Rodriguez <mcgrof@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>