clk: amlogic: move PCLK definition to clkc-utils

clk-regmap was always meant to stay generic, without any amlogic specifics.
The hope was that it could move out of the amlogic directory one day.
Even if this may actually not become true, it should remain generic.

Move the amlogic peripheral clock definition out of clk-regmap header.

Link: https://lore.kernel.org/r/20250825-meson-clk-cleanup-24-v2-5-0f402f01e117@baylibre.com


Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>