iwlagn: add bluetooth stats to debugfs

For WiFi/BT combo devices, add bluetooth statistics counter
read function to debugfs.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-1000.c b/drivers/net/wireless/iwlwifi/iwl-1000.c
index c281d07..8848333 100644
--- a/drivers/net/wireless/iwlwifi/iwl-1000.c
+++ b/drivers/net/wireless/iwlwifi/iwl-1000.c
@@ -222,6 +222,7 @@
 		.rx_stats_read = iwl_ucode_rx_stats_read,
 		.tx_stats_read = iwl_ucode_tx_stats_read,
 		.general_stats_read = iwl_ucode_general_stats_read,
+		.bt_stats_read = iwl_ucode_bt_stats_read,
 	},
 	.recover_from_tx_stall = iwl_bg_monitor_recover,
 	.check_plcp_health = iwl_good_plcp_health,