VOL-2339: DHCP issue on second ONU, when two ONUs exist on same PON

- Process to_remove before to_add items in UpdateFlowsIncrementally
  method
- Sequentially add flows for a given pon, onu, uni inorder to avoid
  PON resource collisions. Used lock per key so that different
  subscribers do not have to wait for each other to add flows.
- Wait for any flow removes for the subscriber to complete before
  adding flows.

Change-Id: I095291b9a53fd0f19dc79f2b44923ec786a26d6e
diff --git a/adaptercore/olt_platform.go b/adaptercore/olt_platform.go
index 0186712..8c7cf8d 100644
--- a/adaptercore/olt_platform.go
+++ b/adaptercore/olt_platform.go
@@ -259,5 +259,9 @@
 	onuID = OnuIDFromUniPortNum(uniPortNo)
 	uniID = UniIDFromPortNum(uniPortNo)
 
+	log.Debugw("flow extract info result",
+		log.Fields{"uniPortNo": uniPortNo, "ponIntf": ponIntf,
+			"onuID": onuID, "uniID": uniID, "inPort": inPort, "ethType": ethType})
+
 	return uniPortNo, ponIntf, onuID, uniID, inPort, ethType, nil
 }