dt-bindings: i2c: renesas,riic: Document RZ/Five SoC

The RIIC block on the RZ/Five SoC is identical to one found on the RZ/G2UL
SoC. "renesas,riic-r9a07g043" compatible string will be used on the
RZ/Five SoC so to make this clear, update the comment to include RZ/Five
SoC.

No driver changes are required as generic compatible string
"renesas,riic-rz" will be used as a fallback on RZ/Five SoC.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>