mac80211: clean up beacon interval settings

We currently have two beacon interval configuration knobs:
hw.conf.beacon_int and vif.bss_info.beacon_int. This is
rather confusing, even though the former is used when we
beacon ourselves and the latter when we are associated to
an AP.

This just deprecates the hw.conf.beacon_int setting in favour
of always using vif.bss_info.beacon_int. Since it touches all
the beaconing IBSS code anyway, we can also add support for
the cfg80211 IBSS beacon interval configuration easily.

NOTE: The hw.conf.beacon_int setting is retained for now due
      to drivers still using it -- I couldn't untangle all
      drivers, some are updated in this patch.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ar9170/main.c b/drivers/net/wireless/ath/ar9170/main.c
index 1b60906..49c729b 100644
--- a/drivers/net/wireless/ath/ar9170/main.c
+++ b/drivers/net/wireless/ath/ar9170/main.c
@@ -1337,7 +1337,7 @@
 			goto out;
 	}
 
-	if (changed & IEEE80211_CONF_CHANGE_BEACON_INTERVAL) {
+	if (changed & BSS_CHANGED_BEACON_INT) {
 		err = ar9170_set_beacon_timers(ar);
 		if (err)
 			goto out;
@@ -1499,6 +1499,9 @@
 #endif /* CONFIG_AR9170_LEDS */
 	}
 
+	if (changed & BSS_CHANGED_BEACON_INT)
+		err = ar9170_set_beacon_timers(ar);
+
 	if (changed & BSS_CHANGED_HT) {
 		/* TODO */
 		err = 0;