ASoC: wm_adsp: Separate some ASoC and generic functions

Split some functions into ASoC and generic portions so that existing
interfaces can be retained whilst allowing the implementation to be
moved out of ASoC.

Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210913160057.103842-8-simont@opensource.cirrus.com


Signed-off-by: Mark Brown <broonie@kernel.org>