cfg80211: force WIPHY_FLAG_CUSTOM_REGULATORY on wiphy_apply_custom_regulatory()

wiphy_apply_custom_regulatory() implies WIPHY_FLAG_CUSTOM_REGULATORY
but we never enforced it, do that now and warn if the driver
didn't set it. All drivers should be following this today already.

Having WIPHY_FLAG_CUSTOM_REGULATORY does not however mean you will
use wiphy_apply_custom_regulatory() though, you may have your own
_orig value set up tools / helpers. The intel drivers are examples
of this type of driver.

Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/reg.c

@@ -1292,6 +1292,10 @@ void wiphy_apply_custom_regulatory(struct wiphy *wiphy,
 	enum ieee80211_band band;
 	unsigned int bands_set = 0;
 
+	WARN(!(wiphy->flags & WIPHY_FLAG_CUSTOM_REGULATORY),
+	     "wiphy should have WIPHY_FLAG_CUSTOM_REGULATORY\n");
+	wiphy->flags |= WIPHY_FLAG_CUSTOM_REGULATORY;
+
 	for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 		if (!wiphy->bands[band])
 			continue;