clk: renesas: Prepare for split of R-Car H3 config symbol

Despite using the same compatible values ("r8a7795"-based) because of
historical reasons, R-Car H3 ES1.x (R8A77950) and R-Car H3 ES2.0+
(R8A77951) are really different SoCs, with different part numbers.
Hence the SoC configuration symbol will be split in two separate config
symbols.

As the Clock Pulse Generator / Module Standby and Software Reset blocks
in both SoCs are very similar, they will keep on sharing a driver.
Extend the dependency of CONFIG_CLK_R8A7795, to prepare for the split.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Link: https://lore.kernel.org/r/20191230080902.2832-1-geert+renesas@glider.be