dt-bindings: soc: rockchip: add initial rk3588 syscon compatibles

Add IOC and PHP GRF syscon compatibles for RK3588.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Jagan Teki <jagan@edgeble.ai>
Link: https://lore.kernel.org/r/20230109155801.51642-2-sebastian.reichel@collabora.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>