HID: elan: Set default_trigger for the mute LED

The mute LED should be automatically turned on/off based
on the audio-card's mixer settings.

Add the standardized default-trigger name for this, so that the alsa
code can turn the LED on/off as appropriate (on supported audio cards).
Reviewed-by: Marek Behún <kabel@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-elan.c

@@ -460,6 +460,7 @@ static int elan_init_mute_led(struct hid_device *hdev)
 	struct led_classdev *mute_led = &drvdata->mute_led;
 
 	mute_led->name = "elan:red:mute";
+	mute_led->default_trigger = "audio-mute";
 	mute_led->brightness_get = elan_mute_led_get_brigtness;
 	mute_led->brightness_set_blocking = elan_mute_led_set_brigtness;
 	mute_led->max_brightness = LED_ON;