Freescale i.MX audio complex with AK4497 DAC

Required properties:

- compatible   : "fsl,imx-audio-ak4497"
- model        : The user-visible name of this sound complex
- audio-cpu    : The phandle of CPU DAI
- audio-codec  : The phandle of the ak4497 audio DAC
- audio-routing : A list of the connections between audio components. Each entry
  is a pair of strings, the first being the connection's sink, the second being
  the connection's source. Valid names could be power supplies, ak4497 pins,
  and the jacks on the board.

Example:

sound {
       compatible = "fsl,imx-audio-ak4497";
       model = "ak4497-audio";
       audio-cpu = <&sai3>;
       audio-codec = <&codec>;
       audio-routing =
               "AOUTLN", "Playback",
               "AOUTLP", "Playback",
               "AOUTRN", "Playback",
               "AOUTRP", "Playback",
};