iwlagn: support dynamic aggregation for BT coex

Use dynamic aggregation threshold if bt traffic load is high
to reduce the impact on aggregated frame.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-6000.c b/drivers/net/wireless/iwlwifi/iwl-6000.c
index c7ff1bd..d8f9df6 100644
--- a/drivers/net/wireless/iwlwifi/iwl-6000.c
+++ b/drivers/net/wireless/iwlwifi/iwl-6000.c
@@ -546,6 +546,7 @@
 	.bt_statistics = true,
 	/* Due to bluetooth, we transmit 2.4 GHz probes only on antenna A */
 	.advanced_bt_coexist = true,
+	.agg_time_limit = BT_AGG_THRESHOLD_DEF,
 	.bt_init_traffic_load = IWL_BT_COEX_TRAFFIC_LOAD_NONE,
 	.bt_prio_boost = IWLAGN_BT_PRIO_BOOST_DEFAULT,
 };