scsi: dc395x: Fix warning using plain integer as NULL

Sparse static analysis tool generates a warning with this message "Using
plain integer as NULL pointer". Fix it.
Signed-off-by: Abhinav Singh <singhabhinav9051571833@gmail.com>
Link: https://lore.kernel.org/r/20231109215049.1466431-1-singhabhinav9051571833@gmail.comSigned-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/dc395x.c

@@ -1366,7 +1366,7 @@ static u8 start_scsi(struct AdapterCtlBlk* acb, struct DeviceCtlBlk* dcb,
 			"command while another command (0x%p) is active.",
 			srb->cmd,
 			acb->active_dcb->active_srb ?
-			    acb->active_dcb->active_srb->cmd : 0);
+			    acb->active_dcb->active_srb->cmd : NULL);
 		return 1;
 	}
 	if (DC395x_read16(acb, TRM_S1040_SCSI_STATUS) & SCSIINTERRUPT) {