* SiRF SoC USP module

Required properties:
- compatible: "sirf,prima2-usp-pcm"
- reg: Base address and size entries:
- dmas: List of DMA controller phandle and DMA request line ordered pairs.
- dma-names: Identifier string for each DMA request line in the dmas property.
  These strings correspond 1:1 with the ordered pairs in dmas.

  One of the DMA channels will be responsible for transmission (should be
  named "tx") and one for reception (should be named "rx").

- clocks: USP controller clock source
- pinctrl-names: Must contain a "default" entry.
- pinctrl-NNN: One property must exist for each entry in pinctrl-names.

Example:
usp0: usp@b0080000 {
	compatible = "sirf,prima2-usp-pcm";
	reg = <0xb0080000 0x10000>;
	clocks = <&clks 28>;
	dmas = <&dmac1 1>, <&dmac1 2>;
	dma-names = "rx", "tx";
	pinctrl-names = "default";
	pinctrl-0 = <&usp0_only_utfs_pins_a>;
};