ASoC: tas2770: Set regcache when shutting down and waking device

Set the regcache to cache data and mark cache as dirty when the device
is shutdown when suspend is called. When the device is woken up then
sync the cache and set to not caching the data.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
Link: https://lore.kernel.org/r/20200923132600.10652-3-dmurphy@ti.com


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