clk: sunxi-ng: Convert early providers to platform drivers

The PRCM CCU drivers depend on clocks provided by other CCU drivers. For
example, the sun8i-r-ccu driver uses the "pll-periph" clock provided by
the SoC's main CCU.

However, sun8i-r-ccu is an early OF clock provider, and many of the
main CCUs (e.g. sun50i-a64-ccu) use platform drivers. This means that
the consumer clocks will be orphaned until the supplier driver is bound.
This can be avoided by converting the remaining CCUs to use platform
drivers. Then fw_devlink will ensure the drivers are bound in the
optimal order.

The sun5i CCU is the only one which actually needs to be an early clock
provider, because it provides the clock for the system timer. That one
is left alone.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20211119033338.25486-4-samuel@sholland.org