dt-bindings: iio: light: Support ROHM BU27034

ROHM BU27034 is an ambient light sesnor with 3 channels and 3 photo diodes
capable of detecting a very wide range of illuminance. Typical application
is adjusting LCD and backlight power of TVs and mobile phones.

Add dt-bindings.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/66a222574176ee2adbfccf6d9a591c04571a18d9.1680263956.git.mazziesaccount@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/light/rohm,bu27034.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/light/rohm,bu27034.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ROHM BU27034 ambient light sensor
+
+maintainers:
+  - Matti Vaittinen <mazziesaccount@gmail.com>
+
+description: |
+  ROHM BU27034 is an ambient light sesnor with 3 channels and 3 photo diodes
+  capable of detecting a very wide range of illuminance. Typical application
+  is adjusting LCD and backlight power of TVs and mobile phones.
+  https://fscdn.rohm.com/en/products/databook/datasheet/ic/sensor/light/bu27034nuc-e.pdf
+
+properties:
+  compatible:
+    const: rohm,bu27034
+
+  reg:
+    maxItems: 1
+
+  vdd-supply: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      light-sensor@38 {
+        compatible = "rohm,bu27034";
+        reg = <0x38>;
+        vdd-supply = <&vdd>;
+      };
+    };
+
+...