ASoC: wm_adsp: Split DSP power operations into helper functions

This is preparation for moving the generic DSP support out of
ASoC. This change separates the generic handling of power and state
transitions from the DAPM API wrapper.
Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210913160057.103842-9-simont@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>