scsi: isci: Use the proper SCSI midlayer interfaces for PI

Use scsi_prot_ref_tag() instead of scsi_get_lba() to get the reference tag
for a given I/O.

Link: https://lore.kernel.org/r/20210806040023.5355-3-martin.petersen@oracle.com


Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>