media: dt-bindings: Add binding for the Sony IMX219 sensor

The IMX219 is an 8MPix CSI2 sensor, supporting 2 or 4 data lanes.
Document the binding for this device.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>

Documentation/devicetree/bindings/media/i2c/imx219.txt

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+* Sony 1/4.0-Inch 8Mpixel CMOS Digital Image Sensor
+
+The Sony imx219 is a 1/4.0-inch CMOS active pixel digital image sensor with
+an active array size of 3280H x 2464V. It is programmable through I2C
+interface. The I2C address is fixed to 0x10 as per sensor data sheet.
+Image data is sent through MIPI CSI-2, which is configured as either 2 or 4
+data lanes.
+
+Required Properties:
+- compatible: value should be "sony,imx219" for imx219 sensor
+- reg: I2C bus address of the device
+- clocks: reference to the xclk input clock.
+- clock-names: should be "xclk".
+- DOVDD-supply: Digital I/O voltage supply, 1.8 volts
+- AVDD-supply: Analog voltage supply, 2.8 volts
+- DVDD-supply: Digital core voltage supply, 1.2 volts
+
+Optional Properties:
+- xclr-gpios: reference to the GPIO connected to the xclr pin, if any. Must be
+	      released after all supplies are applied.
+	      This is an active high signal to the imx219.
+
+The imx219 device node should contain one 'port' child node with
+an 'endpoint' subnode. For further reading on port node refer to
+Documentation/devicetree/bindings/media/video-interfaces.txt.
+
+Endpoint node required properties for CSI-2 connection are:
+- remote-endpoint: a phandle to the bus receiver's endpoint node.
+- clock-lanes: should be set to <0> (clock lane on hardware lane 0)
+- data-lanes: should be set to <1 2>, or  <1 2 3 4> (two or four lane CSI-2
+  supported)
+
+Example:
+	sensor@10 {
+		compatible = "sony,imx219";
+		reg = <0x10>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clocks = <&imx219_clk>;
+		clock-names = "xclk";
+		xclr-gpios = <&gpio_sensor 0 0>;
+		DOVDD-supply = <&vgen4_reg>; /* 1.8v */
+		AVDD-supply = <&vgen3_reg>;  /* 2.8v */
+		DVDD-supply = <&vgen2_reg>;  /* 1.2v */
+
+		imx219_clk: camera-clk {
+			compatible = "fixed-clock";
+			#clock-cells = <0>;
+			clock-frequency = <24000000>;
+		};
+
+		port {
+			sensor_out: endpoint {
+				remote-endpoint = <&csiss_in>;
+				clock-lanes = <0>;
+				data-lanes = <1 2>;
+			};
+		};
+	};