VOL-3735 Retrieve port counters using the GetExtValue(SingleGetValue) rpc from the openolt adapter

Change-Id: I6bce9eb07396fb84e6733beeb81341080243e7a5
diff --git a/pkg/model/flow.go b/pkg/model/flow.go
index 928339c..39bb81b 100644
--- a/pkg/model/flow.go
+++ b/pkg/model/flow.go
@@ -17,7 +17,7 @@
 
 import (
 	"fmt"
-	"github.com/opencord/voltha-protos/v3/go/openflow_13"
+	"github.com/opencord/voltha-protos/v4/go/openflow_13"
 )
 
 type FlowFieldFlag uint64