cfg80211: put core regulatory request into queue

This will simplify the synchronization for pending requests.
Without this we have a race between the core and when we
restore regulatory settings, although this is unlikely
its best to just avoid that race altogether.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Tested-by: Mark Mentovai <mark@moxienet.com>
Tested-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>