* Spreadtrum sound routing driver

This node models spreadtrum sound routing driver

Required properties:

this node allow sound use sound routing
- compatible : "sprd,pcm-routing"
- #sound-dai-cells : only support 0, it means use default
    asoc platform.

Example:
sprd_route_pcm: sprd-routing-pcm {
	compatible = "sprd,pcm-routing";
	#sound-dai-cells = <0>;
};

sprd-audio-card,dai-link@10 {
	...
	plat {
		sound-dai = <&sprd_route_pcm>;
	};
	...
};
