clk: renesas: Add dummy SDnH clock

clk: renesas: 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.

Based on Linux series by Wolfram Sang:
commit a31cf51bf6b4b ("clk: renesas: rcar-gen3: Add dummy SDnH clock"),
commit 1abd04480866c ("clk: renesas: rcar-gen3: Add SDnH clock"),
commit 63494b6f98f26 ("clk: renesas: r8a779a0: Add SDnH clock to V3U")

Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org> # Switch to gen3_clk_get_rate64