cfg80211: enable 5 GHz world roaming channels

The current static world regulatory domain is too restrictive,
we can use some 5 GHz channels world wide so long as they do not
touch frequencies which require DFS. The compromise is we must
also enforce passive scanning and disallow usage of a mode of
operation that beacons: (AP | IBSS | Mesh)

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