arm64: dts: renesas: r8a77965: Add IIC-DVFS device node

Populate the device node for the IIC Bus Interface for DVFS (IIC for
DVFS) on R-Car M3-N, and add an alias to fix its bus number.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>