dt-bindings: input: Convert da906{1,2,3} onkey to json-schema

Convert the da906{1,2,3} onkey device tree binding documentation to
json-schema.

Update MAINTAINERS entries, description and onkey property by
referring to dlg,da9062-onkey binding file.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://lore.kernel.org/r/20240131102656.3379-4-biju.das.jz@bp.renesas.com
Signed-off-by: Lee Jones <lee@kernel.org>

Documentation/devicetree/bindings/input/dlg,da9062-onkey.yaml

@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/dlg,da9062-onkey.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Dialog DA9061/62/63 OnKey Module
+
+maintainers:
+  - Biju Das <biju.das.jz@bp.renesas.com>
+
+description: |
+  This module is part of the DA9061/DA9062/DA9063. For more details about entire
+  DA9062 and DA9061 chips see Documentation/devicetree/bindings/mfd/da9062.txt
+  For DA9063 see Documentation/devicetree/bindings/mfd/dlg,da9063.yaml
+
+  This module provides the KEY_POWER event.
+
+properties:
+  compatible:
+    oneOf:
+      - enum:
+          - dlg,da9062-onkey
+          - dlg,da9063-onkey
+      - items:
+          - const: dlg,da9061-onkey
+          - const: dlg,da9062-onkey
+
+  dlg,disable-key-power:
+    type: boolean
+    description:
+      Disable power-down using a long key-press. If this entry exists
+      the OnKey driver will remove support for the KEY_POWER key press
+      when triggered using a long press of the OnKey.
+
+required:
+  - compatible
+
+additionalProperties: false