Freescale i.MX audio complex with rpmsg devices

Required properties:
- compatible : "fsl,imx-audio-rpmsg"
- model : The user-visible name of this sound complex
- cpu-dai : The phandle of the i.MX rpmsg i2s device.

Example:
sound-rpmsg {
	compatible = "fsl,imx-audio-rpmsg";
	model = "rpmsg-audio";
	cpu-dai = <&rpmsg_i2s>;
};