NVIDIA Tegra audio complex

Required properties:
- compatible : "nvidia,tegra-audio-wm8903"
- clocks : Must contain an entry for each entry in clock-names.
  See ../clocks/clock-bindings.txt for details.
- clock-names : Must include the following entries:
  - pll_a
  - pll_a_out0
  - mclk (The Tegra cdev1/extern1 clock, which feeds the CODEC's mclk)
- 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 WM8903's pins (documented in the WM8903 binding document),
  and the jacks on the board:

  * Headphone Jack
  * Int Spk
  * Mic Jack
  * Int Mic

- nvidia,i2s-controller : The phandle of the Tegra I2S1 controller
- nvidia,audio-codec : The phandle of the WM8903 audio codec

Optional properties:
- nvidia,spkr-en-gpios : The GPIO that enables the speakers
- nvidia,hp-mute-gpios : The GPIO that mutes the headphones
- nvidia,hp-det-gpios : The GPIO that detect headphones are plugged in
- nvidia,int-mic-en-gpios : The GPIO that enables the internal microphone
- nvidia,ext-mic-en-gpios : The GPIO that enables the external microphone
- nvidia,headset : The Mic Jack represents state of the headset microphone pin

Example:

sound {
	compatible = "nvidia,tegra-audio-wm8903-harmony",
		     "nvidia,tegra-audio-wm8903"
	nvidia,model = "tegra-wm8903-harmony";

	nvidia,audio-routing =
		"Headphone Jack", "HPOUTR",
		"Headphone Jack", "HPOUTL",
		"Int Spk", "ROP",
		"Int Spk", "RON",
		"Int Spk", "LOP",
		"Int Spk", "LON",
		"Mic Jack", "MICBIAS",
		"IN1L", "Mic Jack";

	nvidia,i2s-controller = <&i2s1>;
	nvidia,audio-codec = <&wm8903>;

	nvidia,spkr-en-gpios = <&codec 2 0>;
	nvidia,hp-det-gpios = <&gpio 178 0>; /* gpio PW2 */
	nvidia,int-mic-en-gpios = <&gpio 184 0>; /*gpio PX0 */
	nvidia,ext-mic-en-gpios = <&gpio 185 0>; /* gpio PX1 */

	clocks = <&tegra_car 112>, <&tegra_car 113>, <&tegra_car 93>;
	clock-names = "pll_a", "pll_a_out0", "mclk";
};