scsi: ufs-pci: Ensure UFS device is in PowerDown mode for suspend-to-disk ->poweroff()

scsi: ufs-pci: Ensure UFS device is in PowerDown mode for suspend-to-disk ->poweroff()

The expectation for suspend-to-disk is that devices will be powered-off, so
the UFS device should be put in PowerDown mode. If spm_lvl is not 5, then
that will not happen. Change the pm callbacks to force spm_lvl 5 for
suspend-to-disk poweroff.

Link: https://lore.kernel.org/r/20201207083120.26732-3-adrian.hunter@intel.com
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>