wl12xx: add band field to wlvif

add band field into the per-interface data.

mac80211 configures some values (e.g. band, channel)
globally, while we configure them per-interface.

In order to make it easier to keep track of the
configured value for each value while keeping sync
with mac80211, save these values both globally
and per-vif.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>
diff --git a/drivers/net/wireless/wl12xx/event.c b/drivers/net/wireless/wl12xx/event.c
index a47312d..fd2e7b2 100644
--- a/drivers/net/wireless/wl12xx/event.c
+++ b/drivers/net/wireless/wl12xx/event.c
@@ -145,7 +145,7 @@
 		 * BET has only a minor effect in 5GHz and masks
 		 * channel switch IEs, so we only enable BET on 2.4GHz
 		*/
-		if (wl->band == IEEE80211_BAND_2GHZ)
+		if (wlvif->band == IEEE80211_BAND_2GHZ)
 			/* enable beacon early termination */
 			ret = wl1271_acx_bet_enable(wl, wlvif, true);