NVIDIA Tegra audio complex

Required properties:
- compatible : "nvidia,tegra-audio-wm8753"
- nvidia,model : The user-visible name of this sound complex.
- nvidia,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 for sources and
  sinks are the WM8753's pins, and the jacks on the board:

  WM8753 pins:

  * LOUT1
  * LOUT2
  * ROUT1
  * ROUT2
  * MONO1
  * MONO2
  * OUT3
  * OUT4
  * LINE1
  * LINE2
  * RXP
  * RXN
  * ACIN
  * ACOP
  * MIC1N
  * MIC1
  * MIC2N
  * MIC2
  * Mic Bias

  Board connectors:

  * Headphone Jack
  * Mic Jack

- nvidia,i2s-controller : The phandle of the Tegra I2S1 controller
- nvidia,audio-codec : The phandle of the WM8753 audio codec
Example:

sound {
	compatible = "nvidia,tegra-audio-wm8753-whistler",
		     "nvidia,tegra-audio-wm8753"
	nvidia,model = "tegra-wm8753-harmony";

	nvidia,audio-routing =
		"Headphone Jack", "LOUT1",
		"Headphone Jack", "ROUT1";

	nvidia,i2s-controller = <&i2s1>;
	nvidia,audio-codec = <&wm8753>;
};