dt-bindings: i2c: renesas,riic: Document RZ/G2UL SoC

dt-bindings: i2c: renesas,riic: Document RZ/G2UL SoC

Document RZ/G2UL I2C bindings. RZ/G2UL I2C is identical to one found on
the RZ/G2L SoC. No driver changes are required as RZ/G2L compatible
string "renesas,riic-rz" will be used as a fallback.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220425133152.176949-1-biju.das.jz@bp.renesas.com