RK3568平台（显示篇）DRM HDMI驱动程序

一.设备树配置

设备节点vopb下的子节点vopb_out_hdmi通过hdmi_in_vopb（由remote-endpoint属性指定）和hdmi显示接口组成一个连接通路；

设备节点vopl下的子节点vopl_out_hdmi通过hdmi_in_vopl（由remote-endpoint属性指定）和hdmi显示接口组成一个连接通路；

hdmi: hdmi@ff940000 {
		compatible = "rockchip,rk3399-dw-hdmi";
		reg = <0x0 0xff940000 0x0 0x20000>;
		interrupts = <GIC_SPI 23 IRQ_TYPE_LEVEL_HIGH 0>;
		clocks = <&cru PCLK_HDMI_CTRL>,
				 <&cru SCLK_HDMI_SFR>,
				 <&cru SCLK_HDMI_CEC>,
				 <&cru PCLK_VIO_GRF>,
				 <&cru PLL_VPLL>;
		clock-names = "iahb", "i