dt-bindings: serial: renesas,sci: Document RZ/V2L SoC

Add SCI binding documentation for Renesas RZ/V2L SoC. No driver changes
are required as generic compatible string "renesas,sci" will be used as
a fallback.

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/20211221094717.16187-8-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>