dt-bindings: leds: Add document bindings for leds-mt6323

Device Tree Bindings for LED support on MT6323 PMIC

MT6323 LED controller is subfunction provided by MT6323 PMIC, so the LED

controllers are defined as the subnode of the function node provided by MT6323

PMIC controller that is being defined as one kind of Muti-Function Device (MFD)

using shared bus called PMIC wrapper for each subfunction to access remote

MT6323 PMIC hardware.

For MT6323 MFD bindings see:

Documentation/devicetree/bindings/mfd/mt6397.txt

For MediaTek PMIC wrapper bindings see:

Documentation/devicetree/bindings/soc/mediatek/pwrap.txt

Required properties:

- compatible : Must be "mediatek,mt6323-led"

- address-cells : Must be 1

- size-cells : Must be 0

Each led is represented as a child node of the mediatek,mt6323-led that

describes the initial behavior for each LED physically and currently only four

LED child nodes can be supported.

Required properties for the LED child node:

- reg : LED channel number (0..3)

Optional properties for the LED child node:

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

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

- default-state: See Documentation/devicetree/bindings/leds/common.txt

Example:

	mt6323: pmic {

		compatible = "mediatek,mt6323";

		...

		mt6323led: leds {

			compatible = "mediatek,mt6323-led";

			#address-cells = <1>;

			#size-cells = <0>;

			led@0 {

				reg = <0>;

				label = "LED0";

				linux,default-trigger = "timer";

				default-state = "on";

			};

			led@1 {

				reg = <1>;

				label = "LED1";

				default-state = "off";

			};

			led@2 {

				reg = <2>;

				label = "LED2";

				default-state = "on";

			};

		};

	};