Doc/DT: Add DT binding documentation for tpd12s015 encoder

Add DT binding documentation for tpd12s015 encoder
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: NArchit Taneja <archit@ti.com>

Documentation/devicetree/bindings/video/ti,tpd12s015.txt

+TPD12S015 HDMI level shifter and ESD protection chip
+====================================================
+
+Required properties:
+- compatible: "ti,tpd12s015"
+
+Optional properties:
+- gpios: CT CP HPD, LS OE and HPD gpios
+
+Required nodes:
+- Video port 0 for HDMI input
+- Video port 1 for HDMI output
+
+Example
+-------
+
+tpd12s015: encoder@1 {
+	compatible = "ti,tpd12s015";
+
+	gpios = <&gpio2 28 GPIO_ACTIVE_HIGH>,	/* 60, CT CP HPD */
+		<&gpio2 9 GPIO_ACTIVE_HIGH>,	/* 41, LS OE */
+		<&gpio2 31 GPIO_ACTIVE_HIGH>;	/* 63, HPD */
+
+	ports {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		port@0 {
+			reg = <0>;
+
+			tpd12s015_in: endpoint@0 {
+				remote-endpoint = <&hdmi_out>;
+			};
+		};
+
+		port@1 {
+			reg = <1>;
+
+			tpd12s015_out: endpoint@0 {
+				remote-endpoint = <&hdmi_connector_in>;
+			};
+		};
+	};
+};