Device-Tree bindings for tilcdc DRM driver

Required properties:
 - compatible: value should be "ti,am33xx-tilcdc".
 - interrupts: the interrupt number
 - reg: base address and size of the LCDC device

Recommended properties:
 - interrupt-parent: the phandle for the interrupt controller that
   services interrupts for this device.
 - ti,hwmods: Name of the hwmod associated to the LCDC

Optional properties:
 - max-bandwidth: The maximum pixels per second that the memory
   interface / lcd controller combination can sustain
 - max-width: The maximum horizontal pixel width supported by
   the lcd controller.
 - max-pixelclock: The maximum pixel clock that can be supported
   by the lcd controller in KHz.

Optional nodes:

 - port/ports: to describe a connection to an external encoder. The
   binding follows Documentation/devicetree/bindings/graph.txt and
   suppors a single port with a single endpoint.

Example:

	fb: fb@4830e000 {
		compatible = "ti,am33xx-tilcdc";
		reg = <0x4830e000 0x1000>;
		interrupt-parent = <&intc>;
		interrupts = <36>;
		ti,hwmods = "lcdc";

		port {
			lcdc_0: endpoint@0 {
				remote-endpoint = <&hdmi_0>;
			};
		};
	};

	tda19988: tda19988 {
		compatible = "nxp,tda998x";
		reg = <0x70>;

		pinctrl-names = "default", "off";
		pinctrl-0 = <&nxp_hdmi_bonelt_pins>;
		pinctrl-1 = <&nxp_hdmi_bonelt_off_pins>;

		port {
			hdmi_0: endpoint@0 {
				remote-endpoint = <&lcdc_0>;
			};
		};
	};