dt-bindings: iio: light: Add max44009

* MAX44009 Ambient Light Sensor

Required properties:

- compatible: should be "maxim,max44009"

- reg: the I2C address of the device (default is <0x4a>)

Optional properties:

- interrupts: interrupt mapping for GPIO IRQ. Should be configured with

  IRQ_TYPE_EDGE_FALLING.

Refer to interrupt-controller/interrupts.txt for generic interrupt client

node bindings.

Example:

light-sensor@4a {

	compatible = "maxim,max44009";

	reg = <0x4a>;

	interrupt-parent = <&gpio1>;

	interrupts = <17 IRQ_TYPE_EDGE_FALLING>;

};