dt-bindings: leds: document Panasonic AN30259A bindings

* Panasonic AN30259A 3-channel LED driver

The AN30259A is a LED controller capable of driving three LEDs independently. It supports

constant current output and sloping current output modes. The chip is connected over I2C.

Required properties:

	- compatible: Must be "panasonic,an30259a".

	- reg: I2C slave address.

	- #address-cells: Must be 1.

	- #size-cells: Must be 0.

Each LED is represented as a sub-node of the panasonic,an30259a node.

Required sub-node properties:

	- reg: Pin that the LED is connected to. Must be 1, 2, or 3.

Optional sub-node properties:

	- label: see Documentation/devicetree/bindings/leds/common.txt

	- linux,default-trigger: see Documentation/devicetree/bindings/leds/common.txt

Example:

led-controller@30 {

	compatible = "panasonic,an30259a";

	reg = <0x30>;

	#address-cells = <1>;

	#size-cells = <0>;

	led@1 {

		reg = <1>;

		linux,default-trigger = "heartbeat";

		label = "red:indicator";

	};

	led@2 {

		reg = <2>;

		label = "green:indicator";

	};

	led@3 {

		reg = <3>;

		label = "blue:indicator";

	};

};