dt-bindings: arm64: rockchip: add Powkiddy RGB30

The Powkiddy RGB30 is a portable handheld console from Powkiddy which
uses the Rockchip RK3566 SoC.
Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231013183918.225666-5-macroalpha82@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -674,6 +674,11 @@ properties:
           - const: pine64,soquartz
           - const: rockchip,rk3566
 
+      - description: Powkiddy RGB30
+        items:
+          - const: powkiddy,rgb30
+          - const: rockchip,rk3566
+
       - description: Radxa Compute Module 3(CM3)
         items:
           - enum: