iwlwifi: use antenna A only under high BT load

When bluetooth indicated high load, we should use
only antenna A in 2.4 GHz for management frames.
Add this condition to iwl_toggle_tx_ant() to make
sure it'll always be met. Note that scanning has
a separate way of forcing the antenna, because we
should scan on antenna A only regardless of BT
traffic load.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-core.c

@@ -147,6 +147,10 @@ u8 iwl_toggle_tx_ant(struct iwl_priv *priv, u8 ant, u8 valid)
 	int i;
 	u8 ind = ant;
 
+	if (priv->band == IEEE80211_BAND_2GHZ &&
+	    priv->bt_traffic_load >= IWL_BT_COEX_TRAFFIC_LOAD_HIGH)
+		return 0;
+
 	for (i = 0; i < RATE_ANT_NUM - 1; i++) {
 		ind = (ind + 1) < RATE_ANT_NUM ?  ind + 1 : 0;
 		if (valid & BIT(ind))