clk: sunxi: Convert driver private data to platform data

All of the driver private data should really be platform data since it
is determined statically (selected by the compatible string or extracted
from the devicetree). Move everything to platform data, so it can be
provided when binding the driver. This is useful for SPL, or for
instantiating the driver as part of an MFD.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>