dt-bindings: i2c: renesas,iic: Always declare generic compatibility

According to the Hardware User's Manual, automatic transmission for PMIC
control (DVFS) is not available on the R-Car E3 and RZ/G2E SoC.
Experiments showed 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 Gen3-specific and generic versions, and the corresponding
paragraph can be dropped.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Wolfram Sang <wsa@kernel.org>