ina209 properties

Required properties:
- compatible: Must be "ti,ina209"
- reg: I2C address

Optional properties:

- shunt-resistor
	Shunt resistor value in micro-Ohm

Example:

temp-sensor@4c {
	compatible = "ti,ina209";
	reg = <0x4c>;
	shunt-resistor = <5000>;
};