ES7134 i2s DA converter

Required properties:
- compatible : "everest,es7134" or
               "everest,es7144" or
	       "everest,es7154"
- VDD-supply : regulator phandle for the VDD supply
- PVDD-supply: regulator phandle for the PVDD supply for the es7154

Example:

i2s_codec: external-codec {
	compatible = "everest,es7134";
	VDD-supply = <&vcc_5v>;
};
