Allwinner A10 SPI controller

Required properties:
- compatible: Should be "allwinner,sun4-a10-spi".
- reg: Should contain register location and length.
- interrupts: Should contain interrupt.
- clocks: phandle to the clocks feeding the SPI controller. Two are
          needed:
  - "ahb": the gated AHB parent clock
  - "mod": the parent module clock
- clock-names: Must contain the clock names described just above

Example:

spi1: spi@1c06000 {
	compatible = "allwinner,sun4i-a10-spi";
	reg = <0x01c06000 0x1000>;
	interrupts = <11>;
	clocks = <&ahb_gates 21>, <&spi1_clk>;
	clock-names = "ahb", "mod";
	#address-cells = <1>;
	#size-cells = <0>;
};