leds: lp55xx: add DT bindings for LP55231

The TI55231 appears to be fully compatible to the 5523 model from
National Semicondutor. This patch just adds DT bindings for it.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Milo Kim <milo.kim@ti.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/leds-lp5523.c

@@ -1,5 +1,5 @@
 /*
- * lp5523.c - LP5523 LED Driver
+ * lp5523.c - LP5523, LP55231 LED Driver
  *
  * Copyright (C) 2010 Nokia Corporation
  * Copyright (C) 2012 Texas Instruments
@@ -814,6 +814,7 @@ MODULE_DEVICE_TABLE(i2c, lp5523_id);
 #ifdef CONFIG_OF
 static const struct of_device_id of_lp5523_leds_match[] = {
 	{ .compatible = "national,lp5523", },
+	{ .compatible = "ti,lp55231", },
 	{},
 };