ath: add support for proper dynamic regulatory hints

This enables support for dynamic user regulatory hints.
This is enabled only when CFG80211_CERTIFICATION_ONUS
is selected. For US and JP this is explicitly disabled
unless the systems are being used for strict controlled
testing.

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>