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

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

Document RZ/Five (R9A07G043) SYSC bindings. The SYSC block found on the
RZ/Five SoC is almost identical to one found on the RZ/G2UL (and alike)
SoC's. "renesas,r9a07g043-sysc" compatible string will be used on the
RZ/Five SoC so to make this clear, update the comment to include RZ/Five
SoC.

The SYSC block on RZ/Five has no interrupts to the core so to accommodate
this SoC make interrupts{,-names} properties optional.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220722141506.20171-2-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>