Device-Tree bindings for dw hdmi hdcp2

Required properties:
- compatible : Should be "rockchip,rk3399-hdmi-hdcp2".

Example:
	hdmi_hdcp2: hdmi-hdcp2@ff988000 {
		compatible = "rockchip,rk3399-hdmi-hdcp2";
		reg = <0x0 0xff988000 0x0 0x2000>;
		interrupts = <GIC_SPI 22 IRQ_TYPE_LEVEL_HIGH 0>;
		clocks = <&cru ACLK_HDCP22>, <&cru PCLK_HDCP22>,
			 <&cru HCLK_HDCP22>;
		clock-names ="aclk_hdcp2", "pclk_hdcp2", "hdcp2_clk_hdmi";
		status = "disabled";
	};