scsi: qla2xxx: Remove unused struct 'scsi_dif_tuple'

'scsi_dif_tuple' is unused since commit 8cb2049c ("[SCSI] qla2xxx: T10
DIF - Handle uninitalized sectors.").

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://lore.kernel.org/r/20240528215640.91771-1-linux@treblig.org


Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>