dt-bindings: interrupt-controller: renesas,rzg2l-irqc: Document RZ/G3S

Document the RZ/G3S (R9108G045) interrupt controller. This has few extra
functionalities compared with RZ/G2UL but the already existing driver
can still be used.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231120111820.87398-9-claudiu.beznea.uj@bp.renesas.com