zfcp: restore: Dont use 0 to indicate invalid LUN in rec trace

bring back
commit d21e9da
("[SCSI] zfcp: Dont use 0 to indicate invalid LUN in rec trace")
which was lost with
commit ae0904f
("[SCSI] zfcp: Redesign of the debug tracing for recovery actions.")

Signed-off-by: Steffen Maier <maier@linux.vnet.ibm.com>
Fixes: ae0904f ("[SCSI] zfcp: Redesign of the debug tracing for recovery actions.")
Cc: <stable@vger.kernel.org> #2.6.38+
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/s390/scsi/zfcp_dbf.c

@@ -241,7 +241,8 @@ static void zfcp_dbf_set_common(struct zfcp_dbf_rec *rec,
 	if (sdev) {
 		rec->lun_status = atomic_read(&sdev_to_zfcp(sdev)->status);
 		rec->lun = zfcp_scsi_dev_lun(sdev);
-	}
+	} else
+		rec->lun = ZFCP_DBF_INVALID_LUN;
 }
 
 /**