leds: Standardise LED naming scheme

As discussed on LKML some notion of 'function' is needed in
LED naming. This patch adds this to the documentation and
standardises existing LED drivers.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
diff --git a/drivers/misc/asus-laptop.c b/drivers/misc/asus-laptop.c
index 0846c33..3a36a29 100644
--- a/drivers/misc/asus-laptop.c
+++ b/drivers/misc/asus-laptop.c
@@ -239,7 +239,7 @@
 	static int object##_led_wk;					\
 	static DECLARE_WORK(object##_led_work, object##_led_update);	\
 	static struct led_classdev object##_led = {			\
-		.name           = "asus:" ledname,			\
+		.name           = "asus::" ledname,			\
 		.brightness_set = object##_led_set,			\
 	}