* CSR SiRFprimaII Serial Peripheral Interface

Required properties:
- compatible : Should be "sirf,prima2-spi", "sirf,prima2-usp"
               or "sirf,atlas7-usp"
- reg : Offset and length of the register set for the device
- interrupts : Should contain SPI interrupt
- resets: phandle to the reset controller asserting this device in
          reset
  See ../reset/reset.txt for details.
- dmas : Must contain an entry for each entry in clock-names.
  See ../dma/dma.txt for details.
- dma-names : Must include the following entries:
  - rx
  - tx
- clocks : Must contain an entry for each entry in clock-names.
  See ../clocks/clock-bindings.txt for details.

- #address-cells: Number of cells required to define a chip select
                  address on the SPI bus. Should be set to 1.
- #size-cells:    Should be zero.

Optional properties:
- spi-max-frequency: Specifies maximum SPI clock frequency,
                     Units - Hz. Definition as per
                     Documentation/devicetree/bindings/spi/spi-bus.txt
- cs-gpios:     should specify GPIOs used for chipselects.

Example:

spi0: spi@b00d0000 {
	compatible = "sirf,prima2-spi";
	reg = <0xb00d0000 0x10000>;
	interrupts = <15>;
	dmas = <&dmac1 9>,
		<&dmac1 4>;
	dma-names = "rx", "tx";
	#address-cells = <1>;
	#size-cells = <0>;
	clocks = <&clks 19>;
	resets = <&rstc 26>;
};