ASoC: fsl-sai: Add device tree bindings for Freescale SAI.

Freescale Synchronous Audio Interface (SAI).

The SAI is based on I2S module that used communicating with audio codecs,

which provides a synchronous audio interface that supports fullduplex

serial interfaces with frame synchronization such as I2S, AC97, TDM, and

codec/DSP interfaces.

Required properties:

- compatible: Compatible list, contains "fsl,vf610-sai".

- reg: Offset and length of the register set for the device.

- clocks: Must contain an entry for each entry in clock-names.

- clock-names : Must include the "sai" entry.

- dmas : Generic dma devicetree binding as described in

  Documentation/devicetree/bindings/dma/dma.txt.

- dma-names : Two dmas have to be defined, "tx" and "rx".

- pinctrl-names: Must contain a "default" entry.

- pinctrl-NNN: One property must exist for each entry in pinctrl-names.

  See ../pinctrl/pinctrl-bindings.txt for details of the property values.

- big-endian-regs: If this property is absent, the little endian mode will

  be in use as default, or the big endian mode will be in use for all the

  device registers.

- big-endian-data: If this property is absent, the little endian mode will

  be in use as default, or the big endian mode will be in use for all the

  fifo data.

Example:

sai2: sai@40031000 {

	      compatible = "fsl,vf610-sai";

	      reg = <0x40031000 0x1000>;

	      pinctrl-names = "default";

	      pinctrl-0 = <&pinctrl_sai2_1>;

	      clocks = <&clks VF610_CLK_SAI2>;

	      clock-names = "sai";

	      dma-names = "tx", "rx";

	      dmas = <&edma0 0 VF610_EDMA_MUXID0_SAI2_TX>,

		   <&edma0 0 VF610_EDMA_MUXID0_SAI2_RX>;

	      big-endian-regs;

	      big-endian-data;

};