dt-bindings: clk: Convert rockchip,rk3399-cru to DT schema

Convert the rockchip,rk3399-cru binding to DT schema format.
Tested with
ARCH=arm64 make dt_binding_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/clock/rockchip,rk3399-cru.yaml
ARCH=arm64 make dtbs_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/clock/rockchip,rk3399-cru.yaml

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210610175613.167601-1-nfraprado@collabora.com


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