dt-bindings: leds: pca995x: Add binding document for PCA995X chips

The PCA995x chips are I2C controlled LED drivers. Each chip has
up to 16 outputs, each one with an individual 8-bit resolution
PWM for brightness control. Add binding document.
Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230713163516.21644-1-marex@denx.deSigned-off-by: Lee Jones <lee@kernel.org>

Documentation/devicetree/bindings/leds/nxp,pca995x.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/nxp,pca995x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP PCA995x LED controllers
+
+maintainers:
+  - Isai Gaspar <isaiezequiel.gaspar@nxp.com>
+  - Marek Vasut <marex@denx.de>
+
+description:
+  The NXP PCA9952/PCA9955B are programmable LED controllers connected via I2C
+  that can drive 16 separate lines. Each of them can be individually switched
+  on and off, and brightness can be controlled via individual PWM.
+
+  Datasheets are available at
+  https://www.nxp.com/docs/en/data-sheet/PCA9952_PCA9955.pdf
+  https://www.nxp.com/docs/en/data-sheet/PCA9955B.pdf
+
+properties:
+  compatible:
+    enum:
+      - nxp,pca9952
+      - nxp,pca9955b
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+patternProperties:
+  "^led@[0-9a-f]+$":
+    type: object
+    $ref: common.yaml#
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        minimum: 0
+        maximum: 15
+
+    required:
+      - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/leds/common.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        led-controller@1 {
+            compatible = "nxp,pca9955b";
+            reg = <0x01>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            led@0 {
+                reg = <0x0>;
+                color = <LED_COLOR_ID_RED>;
+                function = LED_FUNCTION_POWER;
+            };
+
+            led@2 {
+                reg = <0x2>;
+                color = <LED_COLOR_ID_WHITE>;
+                function = LED_FUNCTION_STATUS;
+            };
+        };
+    };
+
+...