[SCSI] sd: Make sure provisioning mode is reported correctly

The provisioning_mode parameter in sysfs did not get updated in the
SD_LBP_DISABLE case. Make sure the provisioning mode is always set
correctly.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>