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/mac.c b/drivers/net/wireless/ath/ar9170/mac.c
index c8fa307..0e5967d 100644
--- a/drivers/net/wireless/ath/ar9170/mac.c
+++ b/drivers/net/wireless/ath/ar9170/mac.c
@@ -316,9 +316,9 @@
 	u32 v = 0;
 	u32 pretbtt = 0;
 
-	v |= ar->hw->conf.beacon_int;
-
 	if (ar->vif) {
+		v |= ar->vif->bss_conf.beacon_int;
+
 		switch (ar->vif->type) {
 		case NL80211_IFTYPE_MESH_POINT:
 		case NL80211_IFTYPE_ADHOC:
@@ -326,7 +326,7 @@
 			break;
 		case NL80211_IFTYPE_AP:
 			v |= BIT(24);
-			pretbtt = (ar->hw->conf.beacon_int - 6) << 16;
+			pretbtt = (ar->vif->bss_conf.beacon_int - 6) << 16;
 			break;
 		default:
 			break;