leds: trigger: panic: Don't register panic notifier if creating the trigger failed

It doesn't make sense to register the panic notifier if creating the
panic trigger failed.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/8a61e229-5388-46c7-919a-4d18cc7362b2@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: hkallweit

drivers/leds/trigger/ledtrig-panic.c

@@ -64,10 +64,13 @@ static long led_panic_blink(int state)
 
 static int __init ledtrig_panic_init(void)
 {
+	led_trigger_register_simple("panic", &trigger);
+	if (!trigger)
+		return -ENOMEM;
+
 	atomic_notifier_chain_register(&panic_notifier_list,
 				       &led_trigger_panic_nb);
 
-	led_trigger_register_simple("panic", &trigger);
 	panic_blink = led_panic_blink;
 	return 0;
 }