scsi: qla2xxx: Suppress gcc 7 fall-through warnings

Avoid that building with gcc 7 and W=1 triggers warnings similar to the
following:

drivers/scsi/qla2xxx/qla_isr.c:1189:27: warning: this statement may fall through [-Wimplicit-fallthrough=]

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Himanshu Madhani <himanshu.madhani@cavium.com>
Cc: Quinn Tran <quinn.tran@cavium.com>
Cc: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/qla2xxx/qla_target.c b/drivers/scsi/qla2xxx/qla_target.c
index a23107b..067bcc5 100644
--- a/drivers/scsi/qla2xxx/qla_target.c
+++ b/drivers/scsi/qla2xxx/qla_target.c
@@ -450,6 +450,7 @@ void qlt_response_pkt_all_vps(struct scsi_qla_host *vha,
 		ql_dbg(ql_dbg_tgt, vha, 0xe073,
 			"qla_target(%d):%s: CRC2 Response pkt\n",
 			vha->vp_idx, __func__);
+		/* fall through */
 	case CTIO_TYPE7:
 	{
 		struct ctio7_from_24xx *entry = (struct ctio7_from_24xx *)pkt;
@@ -4889,7 +4890,7 @@ static int qlt_24xx_handle_els(struct scsi_qla_host *vha,
 			res = 1;
 			break;
 		}
-		/* drop through */
+		/* fall through */
 	case ELS_LOGO:
 	case ELS_PRLO:
 		spin_lock_irqsave(&ha->tgt.sess_lock, flags);