cfg80211: add regulatory hint disconnect support

This adds a new regulatory hint to be used when we know all
devices have been disconnected and idle. This can happen
when we suspend, for instance. When we disconnect we can
no longer assume the same regulatory rules learned from
a country IE or beacon hints are applicable so restore
regulatory settings to an initial state.

Since driver hints are cached on the wiphy that called
the hint, those hints are not reproduced onto cfg80211
as the wiphy will respect its own wiphy->regd regardless.

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

net/wireless/reg.h

@@ -63,4 +63,22 @@ void regulatory_hint_11d(struct wiphy *wiphy,
 			 u8 *country_ie,
 			 u8 country_ie_len);
 
+/**
+ * regulatory_hint_disconnect - informs all devices have been disconneted
+ *
+ * Regulotory rules can be enhanced further upon scanning and upon
+ * connection to an AP. These rules become stale if we disconnect
+ * and go to another country, whether or not we suspend and resume.
+ * If we suspend, go to another country and resume we'll automatically
+ * get disconnected shortly after resuming and things will be reset as well.
+ * This routine is a helper to restore regulatory settings to how they were
+ * prior to our first connect attempt. This includes ignoring country IE and
+ * beacon regulatory hints. The ieee80211_regdom module parameter will always
+ * be respected but if a user had set the regulatory domain that will take
+ * precedence.
+ *
+ * Must be called from process context.
+ */
+void regulatory_hint_disconnect(void);
+
 #endif  /* __NET_WIRELESS_REG_H */