[SCSI] zfcp: Add comments to switch/case fallthroughs

Add comments where there is a deliberate fall through in switch/case
statements. This makes some code checkers happy and makes it clear
that there is no missing break statement.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/s390/scsi/zfcp_erp.c b/drivers/s390/scsi/zfcp_erp.c
index fdc9b43..3f64ade 100644
--- a/drivers/s390/scsi/zfcp_erp.c
+++ b/drivers/s390/scsi/zfcp_erp.c
@@ -880,6 +880,7 @@
 				zfcp_port_put(port);
 			return ZFCP_ERP_CONTINUES;
 		}
+		/* fall through */
 	case ZFCP_ERP_STEP_NAMESERVER_LOOKUP:
 		if (!port->d_id)
 			return ZFCP_ERP_FAILED;