* Atmel SSC driver.

Required properties:
- compatible: "atmel,at91rm9200-ssc" or "atmel,at91sam9g45-ssc"
	- atmel,at91rm9200-ssc: support pdc transfer
	- atmel,at91sam9g45-ssc: support dma transfer
- reg: Should contain SSC registers location and length
- interrupts: Should contain SSC interrupt


Required properties for devices compatible with "atmel,at91sam9g45-ssc":
- dmas: DMA specifier, consisting of a phandle to DMA controller node,
  the memory interface and SSC DMA channel ID (for tx and rx).
  See Documentation/devicetree/bindings/dma/atmel-dma.txt for details.
- dma-names: Must be "tx", "rx".

Examples:
- PDC transfer:
ssc0: ssc@fffbc000 {
	compatible = "atmel,at91rm9200-ssc";
	reg = <0xfffbc000 0x4000>;
	interrupts = <14 4 5>;
};

- DMA transfer:
ssc0: ssc@f0010000 {
      compatible = "atmel,at91sam9g45-ssc";
      reg = <0xf0010000 0x4000>;
      interrupts = <28 4 5>;
      dmas = <&dma0 1 13>,
	     <&dma0 1 14>;
      dma-names = "tx", "rx";
      pinctrl-names = "default";
      pinctrl-0 = <&pinctrl_ssc0_tx &pinctrl_ssc0_rx>;
      status = "disabled";
};