Pistachio internal DAC DT bindings

Required properties:

  - compatible: "img,pistachio-internal-dac"

  - img,cr-top : Must contain a phandle to the top level control syscon
		 node which contains the internal dac control registers

  - VDD-supply : Digital power supply regulator (+1.8V or +3.3V)

Examples:

internal_dac: internal-dac {
	compatible = "img,pistachio-internal-dac";
	img,cr-top = <&cr_top>;
	VDD-supply = <&supply3v3>;
};
