NVIDIA Tegra 20 I2S controller

Required properties:
- compatible : "nvidia,tegra20-i2s"
- reg : Should contain I2S registers location and length
- interrupts : Should contain I2S interrupt
- nvidia,dma-request-selector : The Tegra DMA controller's phandle and
  request selector for this I2S controller

Example:

i2s@70002800 {
	compatible = "nvidia,tegra20-i2s";
	reg = <0x70002800 0x200>;
	interrupts = < 45 >;
	nvidia,dma-request-selector = < &apbdma 2 >;
};