scsi: pm80xx: Replace magic numbers with device state defines

This improves the code readability.

Link: https://lore.kernel.org/r/20210305060908.2476850-1-ipylypiv@google.com


Acked-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: Igor Pylypiv <ipylypiv@google.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>