Convert the Renesas R-Mobile System Controller (SYSC) Device Tree
binding documentation to json-schema.

Document missing properties.
Drop consumer example, as it does not belong here.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/22150cfd2ef9d57e84eb53a5dfed8379627a9423.1620119210.git.geert+renesas@glider.beSigned-off-by: Rob Herring <robh@kernel.org>