ASoC: wm_adsp: Move DVFS control into codec driver

In theory the ADSP driver should not need to know anything
about the codec it is part of. But the WM5102 needs DVFS
control based on ADSP clocking speed. This was being handled
by bundling part of the knowledge of this into the ADSP driver.

This change moves this handling out of the ADSP driver and
into the WM5102 driver.

Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>