scsi: zfcp: silence -Wimplicit-fallthrough in zfcp_erp_lun_strategy()

For some reason the already existing substring "fall through" in the
comment is not sufficient for GCC to silence -Wimplicit-fallthrough.

  CC [M]  drivers/s390/scsi/zfcp_erp.o
drivers/s390/scsi/zfcp_erp.c: In function 'zfcp_erp_lun_strategy':
drivers/s390/scsi/zfcp_erp.c:1065:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
  if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_OPEN)
      ^
drivers/s390/scsi/zfcp_erp.c:1068:2: note: here
  case ZFCP_ERP_STEP_LUN_CLOSING:
  ^~~~
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/s390/scsi/zfcp_erp.c

@@ -1070,7 +1070,8 @@ static enum zfcp_erp_act_result zfcp_erp_lun_strategy(
 		zfcp_erp_lun_strategy_clearstati(sdev);
 		if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_OPEN)
 			return zfcp_erp_lun_strategy_close(erp_action);
-		/* already closed, fall through */
+		/* already closed */
+		/* fall through */
 	case ZFCP_ERP_STEP_LUN_CLOSING:
 		if (atomic_read(&zfcp_sdev->status) & ZFCP_STATUS_COMMON_OPEN)
 			return ZFCP_ERP_FAILED;