media: dt-bindings: media: Add bindings for OV2685

Add device tree binding documentation for the OV2685 sensor.
Signed-off-by: Shunqian Zheng <zhengsq@rock-chips.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/devicetree/bindings/media/i2c/ov2685.txt

+* Omnivision OV2685 MIPI CSI-2 sensor
+
+Required Properties:
+- compatible: shall be "ovti,ov2685"
+- clocks: reference to the xvclk input clock
+- clock-names: shall be "xvclk"
+- avdd-supply: Analog voltage supply, 2.8 volts
+- dovdd-supply: Digital I/O voltage supply, 1.8 volts
+- dvdd-supply: Digital core voltage supply, 1.8 volts
+- reset-gpios: Low active reset gpio
+
+The device node shall contain one 'port' child node with an
+'endpoint' subnode for its digital output video port,
+in accordance with the video interface bindings defined in
+Documentation/devicetree/bindings/media/video-interfaces.txt.
+The endpoint optional property 'data-lanes' shall be "<1>".
+
+Example:
+&i2c7 {
+	ov2685: camera-sensor@3c {
+		compatible = "ovti,ov2685";
+		reg = <0x3c>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&clk_24m_cam>;
+
+		clocks = <&cru SCLK_TESTCLKOUT1>;
+		clock-names = "xvclk";
+
+		avdd-supply = <&pp2800_cam>;
+		dovdd-supply = <&pp1800>;
+		dvdd-supply = <&pp1800>;
+		reset-gpios = <&gpio2 3 GPIO_ACTIVE_LOW>;
+
+		port {
+			ucam_out: endpoint {
+				remote-endpoint = <&mipi_in_ucam>;
+				data-lanes = <1>;
+			};
+		};
+	};
+};