dt-bindings: iio: add Bosch BMG160 gyroscope sensor

Define bindings for "bosch,bmg160" and "bosch,bmi055_gyro".
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/gyroscope/bmg160.txt

+* Bosch BMG160 triaxial rotation sensor (gyroscope)
+
+Required properties:
+
+  - compatible : should be "bosch,bmg160" or "bosch,bmi055_gyro"
+  - reg : the I2C address of the sensor (0x69)
+
+Optional properties:
+
+  - interrupts : interrupt mapping for GPIO IRQ, it should by configured with
+		flags IRQ_TYPE_EDGE_RISING
+
+Example:
+
+bmg160@69 {
+	compatible = "bosch,bmg160";
+	reg = <0x69>;
+	interrupt-parent = <&gpio6>;
+	interrupts = <18 (IRQ_TYPE_EDGE_RISING)>;
+};