Updated Adapter to support to handle DHCP trap on NNI and packet-in/out and Bug Fixing.
Tested EAPOL/DHCP/HSIA functionality E2E with EdgeCore OLT and TWSH ONU KIT.

patch: PON port is derived from platform and sent to core and bug fixes

Retested EAPOL/DHCP/HSIA use case end to end with EdgeCore OLT and TWSH ONU KIT

Change-Id: I99df82fd7a1385c10878f6fe09ce0d30c48d8e99
diff --git a/vendor/github.com/opencord/voltha-go/rw_core/utils/flow_utils.go b/vendor/github.com/opencord/voltha-go/rw_core/utils/flow_utils.go
index 0c485bb..c2c9287 100644
--- a/vendor/github.com/opencord/voltha-go/rw_core/utils/flow_utils.go
+++ b/vendor/github.com/opencord/voltha-go/rw_core/utils/flow_utils.go
@@ -171,9 +171,11 @@
 
 func (dr *DeviceRules) Copy() *DeviceRules {
 	copyDR := NewDeviceRules()
-	for key, val := range dr.Rules {
-		if val != nil {
-			copyDR.Rules[key] = val.Copy()
+	if dr != nil {
+		for key, val := range dr.Rules {
+			if val != nil {
+				copyDR.Rules[key] = val.Copy()
+			}
 		}
 	}
 	return copyDR