ath9k: simplify regulatory code

Now that cfg80211 has its own regulatory infrastructure we can
condense ath9k's regulatory code considerably. We only keep data
we need to provide our own regulatory_hint(), reg_notifier() and
information necessary for calibration.

Atheros hardware supports 12 world regulatory domains, since these
are custom we apply them through the the new wiphy_apply_custom_regulatory().
Although we have 12 we can consolidate these into 5 structures based on
frequency and apply a different set of flags that differentiate them on
a case by case basis through the reg_notifier().

If CRDA is not found our own custom world regulatory domain is applied,
this is identical to cfg80211's except we enable passive scan on most
frequencies.

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