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/leds/leds-tosa.c b/drivers/leds/leds-tosa.c
index fb2416a..9e0a188 100644
--- a/drivers/leds/leds-tosa.c
+++ b/drivers/leds/leds-tosa.c
@@ -45,13 +45,13 @@
 }
 
 static struct led_classdev tosa_amber_led = {
-	.name			= "tosa:amber",
+	.name			= "tosa:amber:charge",
 	.default_trigger	= "sharpsl-charge",
 	.brightness_set		= tosaled_amber_set,
 };
 
 static struct led_classdev tosa_green_led = {
-	.name			= "tosa:green",
+	.name			= "tosa:green:mail",
 	.default_trigger	= "nand-disk",
 	.brightness_set		= tosaled_green_set,
 };