device-tree bindings for rockchip soc display controller (vop)

VOP (Visual Output Processor) is the Display Controller for the Rockchip
series of SoCs which transfers the image data from a video memory
buffer to an external LCD interface.

Required properties:
- compatible: value should be one of the following
		"rockchip,rk3036-vop";
		"rockchip,rk3126-vop";
		"rockchip,px30-vop-lit";
		"rockchip,px30-vop-big";
		"rockchip,rk3066-vop";
		"rockchip,rk3188-vop";
		"rockchip,rk3288-vop";
		"rockchip,rk3368-vop";
		"rockchip,rk3366-vop";
		"rockchip,rk3399-vop-big";
		"rockchip,rk3399-vop-lit";
		"rockchip,rk3228-vop";
		"rockchip,rk3328-vop";

- reg: Must contain one entry corresponding to the base address and length
	of the register space. Can optionally contain a second entry
	corresponding to the CRTC gamma LUT address.

- interrupts: should contain a list of all VOP IP block interrupts in the
		 order: VSYNC, LCD_SYSTEM. The interrupt specifier
		 format depends on the interrupt controller used.

- clocks: must include clock specifiers corresponding to entries in the
		clock-names property.

- clock-names: Must contain
		aclk_vop: for ddr buffer transfer.
		hclk_vop: for ahb bus to R/W the phy regs.
		dclk_vop: pixel clock.

- resets: Must contain an entry for each entry in reset-names.
  See ../reset/reset.txt for details.
- reset-names: Must include the following entries:
  - axi
  - ahb
  - dclk

- iommus: required a iommu node

- port: A port node with endpoint definitions as defined in
  Documentation/devicetree/bindings/media/video-interfaces.txt.

Example:
SoC specific DT entry:
	vopb: vopb@ff930000 {
		compatible = "rockchip,rk3288-vop";
		reg = <0x0 0xff930000 0x0 0x19c>, <0x0 0xff931000 0x0 0x1000>;
		interrupts = <GIC_SPI 15 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&cru ACLK_VOP0>, <&cru DCLK_VOP0>, <&cru HCLK_VOP0>;
		clock-names = "aclk_vop", "dclk_vop", "hclk_vop";
		resets = <&cru SRST_LCDC1_AXI>, <&cru SRST_LCDC1_AHB>, <&cru SRST_LCDC1_DCLK>;
		reset-names = "axi", "ahb", "dclk";
		iommus = <&vopb_mmu>;
		vopb_out: port {
			#address-cells = <1>;
			#size-cells = <0>;
			vopb_out_edp: endpoint@0 {
				reg = <0>;
				remote-endpoint=<&edp_in_vopb>;
			};
			vopb_out_hdmi: endpoint@1 {
				reg = <1>;
				remote-endpoint=<&hdmi_in_vopb>;
			};
		};
	};