leds: Rename led_set_brightness() to __led_set_brightness()

Rename leds internal interface led_set_brightness() to __led_set_brightness()
to reduce confusion between led_set_brightness() and the external interface
led_brightness_set(). led_brightness_set() cancels the timer and then calls
led_set_brightness().

Signed-off-by: Shuah Khan <shuahkhan@gmail.com>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>
diff --git a/drivers/leds/ledtrig-heartbeat.c b/drivers/leds/ledtrig-heartbeat.c
index a019fbb..1edc746 100644
--- a/drivers/leds/ledtrig-heartbeat.c
+++ b/drivers/leds/ledtrig-heartbeat.c
@@ -74,7 +74,7 @@
 		break;
 	}
 
-	led_set_brightness(led_cdev, brightness);
+	__led_set_brightness(led_cdev, brightness);
 	mod_timer(&heartbeat_data->timer, jiffies + delay);
 }