dt-bindings: i2c: renesas,riic: Document R9A09G057 support

dt-bindings: i2c: renesas,riic: Document R9A09G057 support

Document support for the I2C Bus Interface (RIIC) available in the
Renesas RZ/V2H(P) (R9A09G057) SoC.

The RIIC interface in the Renesas RZ/V2H(P) differs from RZ/A in a
couple of ways:
- Register offsets for the RZ/V2H(P) SoC differ from those of the
  RZ/A SoC.
- RZ/V2H register access is limited to 8-bit, whereas RZ/A supports
  8/16/32-bit.
- RZ/V2H has bit differences in the slave address register.

To accommodate these differences, a new compatible string
"renesas,riic-r9a09g057" is added.

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>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>