clk: clk-apple-nco: Add driver for Apple NCO

Add a common clock driver for NCO blocks found on Apple SoCs where they
are typically the generators of audio clocks.

Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Link: https://lore.kernel.org/r/20220208183411.61090-3-povik+lin@cutebit.org


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