dt-bindings: power: renesas,rzg2l-sysc: Document RZ/V2L SoC

Add DT binding documentation for the SYSC controller found on the RZ/V2L
SoC.  This SYSC controller is almost identical to the one found on the
RZ/G2L SoC, the only difference being that SYSC on RZ/V2L has an
additional register to control the DRP-AI.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220110134659.30424-2-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>