iwlagn: enable BT session 2 type UART for 2000 series

For 2000 series device, use session 2 type of BT UART message

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-core.h b/drivers/net/wireless/iwlwifi/iwl-core.h
index e0ec170..909b42d 100644
--- a/drivers/net/wireless/iwlwifi/iwl-core.h
+++ b/drivers/net/wireless/iwlwifi/iwl-core.h
@@ -339,6 +339,7 @@
 	u8 ampdu_factor;
 	u8 ampdu_density;
 	bool bt_sco_disable;
+	bool bt_session_2;
 };
 /*
  * @use_rts_for_aggregation: use rts/cts protection for HT traffic