SDCA Jack Fixups

Merge series from Charles Keepax <ckeepax@opensource.cirrus.com>:

Some fixups to the jack handling, adding some necessary hooks to connect
things with the machine driver. I have split these out from the system
suspend chain as that has been generating a fair amount of discussion
and getting these 3 merged is far more important to get basic
functionality working smoothly. I will do a spin of the system suspend
stuff soon, if either no new comments pop up, or we reach some consensus
on how to proceed.