[SCSI] scsi_debug: Implement support for DIF Type 2

Add support for 32-byte READ/WRITE as well as DIF Type 2 protection.

Reject protected 10/12/16 byte READ/WRITE commands when Type 2 is
enabled.

Verify Type 2 reference tag according to Expected Initial LBA in 32-byte
CDB.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>