* ZTE ZX296702 DMA controller

Required properties:
- compatible: Should be "zte,zx296702-dma"
- reg: Should contain DMA registers location and length.
- interrupts: Should contain one interrupt shared by all channel
- #dma-cells: see dma.txt, should be 1, para number
- dma-channels: physical channels supported
- dma-requests: virtual channels supported, each virtual channel
		have specific request line
- clocks: clock required

Example:

Controller:
	dma: dma-controller@09c00000{
		compatible = "zte,zx296702-dma";
		reg = <0x09c00000 0x1000>;
		clocks = <&topclk ZX296702_DMA_ACLK>;
		interrupts = <GIC_SPI 66 IRQ_TYPE_LEVEL_HIGH>;
		#dma-cells = <1>;
		dma-channels = <24>;
		dma-requests = <24>;
	};

Client:
Use specific request line passing from dmax
For example, spdif0 tx channel request line is 4
	spdif0: spdif0@b004000 {
		#sound-dai-cells = <0>;
		compatible = "zte,zx296702-spdif";
		reg = <0x0b004000 0x1000>;
		clocks = <&lsp0clk ZX296702_SPDIF0_DIV>;
		clock-names = "tx";
		interrupts = <GIC_SPI 21 IRQ_TYPE_LEVEL_HIGH>;
		dmas = <&dma 4>;
		dma-names = "tx";
	}