dt-bindings: soc: renesas: renesas,rzg2l-sysc: Document RZ/G3S SoC

dt-bindings: soc: renesas: renesas,rzg2l-sysc: Document RZ/G3S SoC

Document RZ/G3S (R9A08G045) SYSC bindings. The SYSC block found on the
RZ/G3S SoC is similar to the one found on the RZ/G2UL.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230912045157.177966-4-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>