[VOL-4371]  Voltha protos cleanup

Details can be found at:
https://docs.google.com/document/d/1UzfuiPzxYYTULyERk8nKfgzW9QAnwEdtfw_J4UoFyYo/edit

Change-Id: Iad2efddf306234e282af5d518fd435a6b50b1c41
diff --git a/protos/voltha_protos/openflow_13.proto b/protos/voltha_protos/openflow_13.proto
index 3a6a315..2f6791e 100755
--- a/protos/voltha_protos/openflow_13.proto
+++ b/protos/voltha_protos/openflow_13.proto
@@ -2308,4 +2308,10 @@
         ofp_port_status port_status = 2;
         ofp_error_msg error = 3;
     }
+}
+
+// Additional information required to process flow at device adapters
+message FlowMetadata {
+    // Meters associated with flow-update to adapter
+    repeated openflow_13.ofp_meter_config meters = 1;
 }
\ No newline at end of file