FROMLIST: virtio_mmio: pm: Add notification handlers for restore and freeze

Handle restore and freeze notifications from the PM core. Expose
these to individual virtio drivers that can quiesce and resume vq
operations.

Signed-off-by: Yurii Danilovskyi <glyd@opensynergy.com>
Signed-off-by: Mikhail Golubev <Mikhail.Golubev@opensynergy.com>

Bug: 141626390
Link: https://lore.kernel.org/all/20211214161124.GA202691@opensynergy.com/


Change-Id: Ie53a16991b10c02ac125a55c4bbf04d89f0a365e
Signed-off-by: Mikhail Golubev <Mikhail.Golubev@opensynergy.com>