scsi: hpsa: fix volume offline state

In a previous patch a hpsa_scsi_dev_t.volume_offline update line has
been removed, so let us put it back..

Fixes: 85b29008

 (hpsa: update check for logical volume status)
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Don Brace <don.brace@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>