clk: cs2000-cp: convert driver to regmap

Regmap gives us caching, debugging infrastructure and other things for
free and does away with open-coded bit-fiddling implementations.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Link: https://lore.kernel.org/r/20220125093336.226787-10-daniel@zonque.org


Signed-off-by: Stephen Boyd <sboyd@kernel.org>