Improve cs42l43 suspend/IRQ interactions

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

cs42l43 uses pm_runtime_force_suspend() during system suspend, however
this means care must be taken that IRQ handler code isn't running when
entering system suspend as force suspend will ignore that the handler
is holding a pm reference. Typically the result of this is just a few
error messages, but better to improve the handling and ensure that all
IRQ processing is synchronised in before system suspend.