* Hisilicon 6210 i2s controller

Required properties:

- compatible: should be one of the following:
   - "hisilicon,hi3660-i2s-1.0"
- reg: physical base address of the i2s controller unit and length of
   memory mapped region.
- interrupts: should contain the i2s interrupt.
- clocks: a list of phandle + clock-specifier pairs, one for each entry
  in clock-names.
- clock-names: should contain following:
   - "dacodec"
   - "i2s-base"
- dmas: DMA specifiers for tx dma. See the DMA client binding,
  Documentation/devicetree/bindings/dma/dma.txt
- dma-names: should be "tx" and "rx"
- hisilicon,sysctrl-syscon: phandle to sysctrl syscon
- #sound-dai-cells: Should be set to 1 (for multi-dai)

Example for the hi3660 i2s controller:

	i2s2: hisi_i2s {
		compatible = "hisilicon,hi3660-i2s-1.0";
		reg = <0x0 0xe804f800 0x0 0x400>,
			  <0x0 0xe804e000 0x0 0x400>;
		pinctrl-names = "default";
		pinctrl-0 = <&i2s2_pmx_func &i2s2_cfg_func>;
		dmas = <&asp_dmac 18 &asp_dmac 19>;
		dma-names = "rx", "tx";
		#sound-dai-cells = <0>;
	};

	sound {
		compatible = "simple-audio-card";
		simple-audio-card,name = "hikey-hdmi";
		simple-audio-card,format = "i2s";

		simple-audio-card,bitclock-master = <&sound_master>;
		simple-audio-card,frame-master = <&sound_master>;

		sound_master: simple-audio-card,cpu {
			sound-dai = <&i2s2>;
		};

		simple-audio-card,codec {
			sound-dai = <&adv7533>;
		};
	};