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/ps.c b/drivers/net/wireless/wl12xx/ps.c
index 8cd81ce..8153408 100644
--- a/drivers/net/wireless/wl12xx/ps.c
+++ b/drivers/net/wireless/wl12xx/ps.c
@@ -178,7 +178,7 @@
 		wl1271_debug(DEBUG_PSM, "leaving psm");
 
 		/* disable beacon early termination */
-		if (wl->band == IEEE80211_BAND_2GHZ) {
+		if (wlvif->band == IEEE80211_BAND_2GHZ) {
 			ret = wl1271_acx_bet_enable(wl, wlvif, false);
 			if (ret < 0)
 				return ret;