dt-bindings: power: rockchip: Add bindings for RK3568 Soc

Add the compatible string for RK3568 SoC.

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210417112952.8516-15-jbx6244@gmail.com


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