dt-bindings: iio: light: add ltr390

Add binding for Lite-On LTR390 which is an Ambient/UV light sensor that
communicates over i2c with an address of 0x53.

Datasheet: https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdfReviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Anshul Dalal <anshulusr@gmail.com>
Link: https://lore.kernel.org/r/20231208102211.413019-1-anshulusr@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/light/liteon,ltr390.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/light/liteon,ltr390.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Lite-On LTR390 ALS and UV Sensor
+
+description: |
+  The Lite-On LTR390 is an ALS (Ambient Light Sensor) and a UV sensor in a
+  single package with i2c address of 0x53.
+
+  Datasheet:
+    https://optoelectronics.liteon.com/upload/download/DS86-2015-0004/LTR-390UV_Final_%20DS_V1%201.pdf
+
+maintainers:
+  - Anshul Dalal <anshulusr@gmail.com>
+
+properties:
+  compatible:
+    enum:
+      - liteon,ltr390
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+    description: |
+      Level interrupt pin with open drain output.
+      The sensor pulls this pin low when the measured reading is greater than
+      some configured threshold.
+
+  vdd-supply: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        light-sensor@53 {
+            compatible = "liteon,ltr390";
+            reg = <0x53>;
+            interrupts = <18 IRQ_TYPE_EDGE_FALLING>;
+            vdd-supply = <&vdd_regulator>;
+        };
+    };