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/input/misc/wistron_btns.c b/drivers/input/misc/wistron_btns.c
index b438d99..72176f3d 100644
--- a/drivers/input/misc/wistron_btns.c
+++ b/drivers/input/misc/wistron_btns.c
@@ -998,12 +998,12 @@
 }
 
 static struct led_classdev wistron_mail_led = {
-	.name			= "mail:green",
+	.name			= "wistron:green:mail",
 	.brightness_set		= wistron_mail_led_set,
 };
 
 static struct led_classdev wistron_wifi_led = {
-	.name			= "wifi:red",
+	.name			= "wistron:red:wifi",
 	.brightness_set		= wistron_wifi_led_set,
 };