Device-Tree bindings for rockchip hdmi driver

Required properties:
- compatible: value should be following:
	"rockchip,rk3036-hdmi",
	"rockchip,rk3066-hdmi",
	"rockchip,rk312x-hdmi",
	"rockchip,rk3288-hdmi",
	"rockchip,rk3368-hdmi",
	"rockchip,rk3399-hdmi",
- reg: physical base address of the hdmi and length of memory mapped
        region.
- interrupts: interrupt number to the cpu.
- pinctrl-names: must contain a "default" entry.
- pinctrl-0: pin control group to be used for this controller.
- pinctrl-1: pin control group to be used for gpio.
- clocks: must include clock specifiers corresponding to entries in the
        clock-names property.
- clocks-names: list of clock names sorted in the same order as the clocks
               property. Must contain "pclk_hdmi" and "hdcp_clk_hdmi".
- rockchip,hdmi_audio_source: hdmi audio source that is described as follow
	<0>: hdmi audio source from the I2S interface
	<1>: hdmi audio source from the SPDIF interface				
- rockchip,hdmi_video_source: hdmi video source that is described as follow
	<DISPLAY_SOURCE_LCDC0> hdmi video source from LCDC0/VOP0
	<DISPLAY_SOURCE_LCDC1> hdmi video source from LCDC1/VOP1
- rockchip,hdcp_enable: hdmi hdcp function is described as follow
	<0>: hdcp function is disabled.
	<1>: hdcp function is enabled.
- rockchip,cec_enable: hdmi cec function is described as follow
	<0>: cec function is disabled.
	<1>: cec function is enabled.
- rockchip,defaultmode: hdmi default output video mode.
Example:

	hdmi: hdmi@ff980000 {
                compatible = "rockchip,rk3288-hdmi";
                reg = <0xff980000 0x20000>;
                interrupts = <GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
                pinctrl-names = "default", "gpio";
                pinctrl-0 = <&i2c5_sda &i2c5_scl>;
                pinctrl-1 = <&i2c5_gpio>;
                clocks = <&clk_gates16 9>, <&clk_gates5 12>;
                clock-names = "pclk_hdmi", "hdcp_clk_hdmi";
		rockchip,hdmi_video_source = <DISPLAY_SOURCE_LCDC0>;
		rockchip,hdmi_audio_source = <0>;
		rockchip,hdcp_enable = <0>;
		rockchip,cec_enable = <0>;
        };