ASoC: core: Support suspend to disk

Use the same pm_ops for all system suspend and resume paths. This isn't
ideal for suspend to disk with older CODECs as we'll suspend and then
resume the CODEC before powering off all of which takes a long time due
to VMID ramps but it's very simple to implement and for modern CODECs the
overhead should be minimal.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>