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>

Documentation/devicetree/bindings/leds/leds-lp55xx.txt

@@ -1,7 +1,7 @@
-Binding for National Semiconductor LP55xx Led Drivers
+Binding for TI/National Semiconductor LP55xx Led Drivers
 
 Required properties:
-- compatible: "national,lp5521" or "national,lp5523"
+- compatible: "national,lp5521" or "national,lp5523" or "ti,lp5562"
 - reg: I2C slave address
 - clock-mode: Input clock mode, (0: automode, 1: internal, 2: external)
 
@@ -112,3 +112,36 @@ lp5523@32 {
 		max-cur = /bits/ 8 <0x20>;
 	};
 };
+
+example 3) LP5562
+4 channels are defined.
+
+lp5562@30 {
+	compatible = "ti,lp5562";
+	reg = <0x30>;
+	clock-mode = /bits/8 <2>;
+
+	chan0 {
+		chan-name = "R";
+		led-cur = /bits/ 8 <0x20>;
+		max-cur = /bits/ 8 <0x60>;
+	};
+
+	chan1 {
+		chan-name = "G";
+		led-cur = /bits/ 8 <0x20>;
+		max-cur = /bits/ 8 <0x60>;
+	};
+
+	chan2 {
+		chan-name = "B";
+		led-cur = /bits/ 8 <0x20>;
+		max-cur = /bits/ 8 <0x60>;
+	};
+
+	chan3 {
+		chan-name = "W";
+		led-cur = /bits/ 8 <0x20>;
+		max-cur = /bits/ 8 <0x60>;
+	};
+};