Mediatek MT5870 spi controller

Required properties:

- compatible: must be "mediatek,mt5870-spi"
- reg: physical base address and length for this controller
- #address-cells: should be 1.
- #size-cells: should be 0.
- clocks: XTAL

Example:

spi@0x1f2a7400 {
	compatible = "mediatek,mt5870-spi";
	reg = <0 0x1f2a7400 0 0x200>;
	interrupts = <0x0 0x43 0x4>;
	mspi_channel = <0>;
	#address-cells = <1>;
	#size-cells = <0>;
};
