dt-bindings: i2c: renesas,rcar-i2c: Add r8a779g0 support

Document support for the I2C Bus Interfaces in the Renesas R-Car V4H
(R8A779G0) SoC.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>