ARM: dts: rzg1: Add generic compatible strings to IIC nodes

According to the Hardware User's Manual, automatic transmission for PMIC
control (DVFS) is not available" on RZ/G1 SoCs.  This really means that
support for automatic DVFS is not present, while the IIC automatic
transmission feature itself is still available, albeit not super useful.

Hence there is no longer a reason not to declare compatibility with the
R-Car Gen2-specific and generic versions.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/573c8ca99f3924a96000fb328a84f1f6d421c6af.1624013699.git.geert+renesas@glider.be