Freescale Digital Audio Mux (AUDMUX) device

Required properties:
- compatible : "fsl,imx21-audmux" for AUDMUX version firstly used on i.MX21,
  or "fsl,imx31-audmux" for the version firstly used on i.MX31.
- reg : Should contain AUDMUX registers location and length

Example:

audmux@021d8000 {
        compatible = "fsl,imx6q-audmux", "fsl,imx31-audmux";
        reg = <0x021d8000 0x4000>;
};