Phytium SPI controller

Required properties:
- compatible: should be "phytium,spi"
- #address-cells: see spi-bus.txt
- #size-cells: see spi-bus.txt
- reg: address and length of the spi master registers
- interrupts: should contain one interrupt
- clocks: spi clock phandle
- num-cs: see spi-bus.txt

Optional properties:
- cs-gpios: see spi-bus.txt

Example:


spi0: spi@2800c000 {
	compatible = "phytium,spi";
	interrupts = <GIC_SPI 18 IRQ_TYPE_LEVEL_HIGH>;
	reg = <0x0 0x2800c000 0x0 0x1000>;
	clocks = <&sysclk_48mhz>;
	num-cs = <4>;
};