clk: renesas: rcar-gen3: Add dummy SDnH clock

clk: renesas: rcar-gen3: Add dummy SDnH clock

Currently, SDnH is handled together with SDn. This caused lots of
problems, so we want SDnH as a separate clock. Introduce a dummy SDnH
type here which creates a fixed-factor clock with factor 1. That allows
us to convert the per-SoC CPG drivers while keeping the old behaviour
for now. A later patch then will add the proper functionality.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20211110191610.5664-2-wsa+renesas@sang-engineering.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>