Device-Tree bindings for tilcdc DRM TFP410 output driver

Required properties:
 - compatible: value should be "ti,tilcdc,tfp410".
 - i2c: the phandle for the i2c device to use for DDC

Recommended properties:
 - pinctrl-names, pinctrl-0: the pincontrol settings to configure
   muxing properly for pins that connect to TFP410 device
 - powerdn-gpio: the powerdown GPIO, pulled low to power down the
   TFP410 device (for DPMS_OFF)

Example:

	dvicape {
		compatible = "ti,tilcdc,tfp410";
		i2c = <&i2c2>;
		pinctrl-names = "default";
		pinctrl-0 = <&bone_dvi_cape_dvi_00A1_pins>;
		powerdn-gpio = <&gpio2 31 0>;
	};