Add system suspend functions to handle clean power-down on suspend and
restoring registers on resume.

The jack state could change during suspend. Plug->unplug and unplug->plug
are straightforward because this looks no different from any other plug
state change - there will be a plugged or unplugged interrupt pending.
The jack could be unplugged and a different type of jack plugged, and on
resume the plug state would not have changed. Setting plug_state back to
TS_TRANS (transitioning) will make the next plug interrupt after resume
run a type detection.

During system suspend any jack plug/unplug and button events will not be
reported or generate a system wakeup. If the plug state or headset type
has changed it will be reported after resume.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220121120412.672284-4-rf@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>