leds: old enums are not really applicable to new code

Warn about old defines that probably should not be used.
Signed-off-by: Pavel Machek <pavel@ucw.cz>

include/linux/leds.h

@@ -25,6 +25,7 @@ struct device_node;
  * LED Core
  */
 
+/* This is obsolete/useless. We now support variable maximum brightness. */
 enum led_brightness {
 	LED_OFF		= 0,
 	LED_ON		= 1,