iwlwifi: add option to disalbe LED

Led has no use for some platform.
Add additional module parameter option to disable LED

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-led.c b/drivers/net/wireless/iwlwifi/iwl-led.c
index eca7908..8761438 100644
--- a/drivers/net/wireless/iwlwifi/iwl-led.c
+++ b/drivers/net/wireless/iwlwifi/iwl-led.c
@@ -177,6 +177,10 @@
 	int mode = iwlagn_mod_params.led_mode;
 	int ret;
 
+	if (mode == IWL_LED_DISABLE) {
+		IWL_INFO(priv, "Led disabled\n");
+		return;
+	}
 	if (mode == IWL_LED_DEFAULT)
 		mode = cfg(priv)->led_mode;