iwlwifi: introduce iwl_advanced_bt_coexist()

We use priv->cfg->bt_params && priv->cfg->bt_params->advanced_bt_coexist
conditional in few places, merge it into one function.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-debugfs.c b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
index 418c8ac..bde16ac 100644
--- a/drivers/net/wireless/iwlwifi/iwl-debugfs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
@@ -1771,7 +1771,7 @@
 	DEBUGFS_ADD_FILE(rxon_flags, dir_debug, S_IWUSR);
 	DEBUGFS_ADD_FILE(rxon_filter_flags, dir_debug, S_IWUSR);
 	DEBUGFS_ADD_FILE(wd_timeout, dir_debug, S_IWUSR);
-	if (priv->cfg->bt_params && priv->cfg->bt_params->advanced_bt_coexist)
+	if (iwl_advanced_bt_coexist(priv))
 		DEBUGFS_ADD_FILE(bt_traffic, dir_debug, S_IRUSR);
 	if (priv->cfg->base_params->sensitivity_calib_by_driver)
 		DEBUGFS_ADD_BOOL(disable_sensitivity, dir_rf,