leds: allow led-drivers to use a variable range of brightness values

This patch allows drivers to override the default maximum brightness value
of 255.  We take care to preserve backwards-compatibility as much as
possible, so that user-space ABI doesn't change for existing drivers.
LED trigger code has also been updated to use the per-LED maximum.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
diff --git a/drivers/leds/ledtrig-ide-disk.c b/drivers/leds/ledtrig-ide-disk.c
index 883a577..ec099fc 100644
--- a/drivers/leds/ledtrig-ide-disk.c
+++ b/drivers/leds/ledtrig-ide-disk.c
@@ -37,7 +37,8 @@
 {
 	if (ide_lastactivity != ide_activity) {
 		ide_lastactivity = ide_activity;
-		led_trigger_event(ledtrig_ide, LED_FULL);
+		/* INT_MAX will set each LED to its maximum brightness */
+		led_trigger_event(ledtrig_ide, INT_MAX);
 		mod_timer(&ledtrig_ide_timer, jiffies + msecs_to_jiffies(10));
 	} else {
 		led_trigger_event(ledtrig_ide, LED_OFF);