arm64: dts: r8a7795: Add I2C for DVFS core to dtsi

This patch adds I2C for DVFS device support for R8A7795 SoC.

Signed-off-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
Signed-off-by: Dien Pham <dien.pham.ry@rvc.renesas.com>
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>