iwlwifi: introduce iwl_bt_statistics

We use priv->cfg->bt_params && priv->cfg->bt_params->bt_statistics
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 bde16ac..bdcb742 100644
--- a/drivers/net/wireless/iwlwifi/iwl-debugfs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
@@ -1765,7 +1765,7 @@
 		DEBUGFS_ADD_FILE(chain_noise, dir_debug, S_IRUSR);
 	if (priv->cfg->base_params->ucode_tracing)
 		DEBUGFS_ADD_FILE(ucode_tracing, dir_debug, S_IWUSR | S_IRUSR);
-	if (priv->cfg->bt_params && priv->cfg->bt_params->bt_statistics)
+	if (iwl_bt_statistics(priv))
 		DEBUGFS_ADD_FILE(ucode_bt_stats, dir_debug, S_IRUSR);
 	DEBUGFS_ADD_FILE(reply_tx_error, dir_debug, S_IRUSR);
 	DEBUGFS_ADD_FILE(rxon_flags, dir_debug, S_IWUSR);