wl12xx: implement set_bitrate_mask callback

Save the configured bitrate, and use the min allowed rate
as the basic rate (e.g. when scanning).

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>
diff --git a/drivers/net/wireless/wl12xx/wl12xx.h b/drivers/net/wireless/wl12xx/wl12xx.h
index 3ceb20c..45f03f5 100644
--- a/drivers/net/wireless/wl12xx/wl12xx.h
+++ b/drivers/net/wireless/wl12xx/wl12xx.h
@@ -526,6 +526,7 @@
 	u32 basic_rate_set;
 	u32 basic_rate;
 	u32 rate_set;
+	u32 bitrate_masks[IEEE80211_NUM_BANDS];
 
 	/* The current band */
 	enum ieee80211_band band;