dt-bindings: hwmon: Add ina3221 documentation

Texas Instruments INA3221 Device Tree Bindings

1) ina3221 node

  Required properties:

  - compatible: Must be "ti,ina3221"

  - reg: I2C address

  Optional properties:

  = The node contains optional child nodes for three channels =

  = Each child node describes the information of input source =

  - #address-cells: Required only if a child node is present. Must be 1.

  - #size-cells: Required only if a child node is present. Must be 0.

2) child nodes

  Required properties:

  - reg: Must be 0, 1 or 2, corresponding to IN1, IN2 or IN3 port of INA3221

  Optional properties:

  - label: Name of the input source

  - shunt-resistor-micro-ohms: Shunt resistor value in micro-Ohm

Example:

ina3221@40 {

	compatible = "ti,ina3221";

	reg = <0x40>;

	#address-cells = <1>;

	#size-cells = <0>;

	input@0 {

		reg = <0x0>;

		status = "disabled";

	};

	input@1 {

		reg = <0x1>;

		shunt-resistor-micro-ohms = <5000>;

	};

	input@2 {

		reg = <0x2>;

		label = "VDD_5V";

		shunt-resistor-micro-ohms = <5000>;

	};

};