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.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>