leds: lp5562: support the device tree feature

The LP55xx DT structure is applicable to the LP5562 device.
The driver and documentation are updated.

Compatible property of the DT
: LP5521 and LP5223 were manufactured by National Semiconductor.
  LP5562 is a new device from Texas Instruments.

Cc: Gabriel Fernandez <gabriel.fernandez@stericsson.com>
Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/leds-lp5562.c

@@ -515,12 +515,20 @@ static int lp5562_probe(struct i2c_client *client,
 	int ret;
 	struct lp55xx_chip *chip;
 	struct lp55xx_led *led;
-	struct lp55xx_platform_data *pdata = client->dev.platform_data;
+	struct lp55xx_platform_data *pdata;
+	struct device_node *np = client->dev.of_node;
 
-	if (!pdata) {
-		dev_err(&client->dev, "no platform data\n");
-		return -EINVAL;
+	if (!client->dev.platform_data) {
+		if (np) {
+			ret = lp55xx_of_populate_pdata(&client->dev, np);
+			if (ret < 0)
+				return ret;
+		} else {
+			dev_err(&client->dev, "no platform data\n");
+			return -EINVAL;
+		}
 	}
+	pdata = client->dev.platform_data;
 
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
 	if (!chip)
@@ -579,6 +587,7 @@ static int lp5562_remove(struct i2c_client *client)
 
 static const struct i2c_device_id lp5562_id[] = {
 	{ "lp5562", 0 },
+	{ "ti,lp5562", 0 }, /* OF compatible */
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, lp5562_id);