VOL-1123 Specify serial number for Ponsim v2 ONU on command line

Change-Id: I85a15c0e710f22d2869fbe47976036cfa1ee610d
diff --git a/voltha/adapters/ponsim_olt/ponsim_olt.py b/voltha/adapters/ponsim_olt/ponsim_olt.py
index 92a5a0a..64357df 100644
--- a/voltha/adapters/ponsim_olt/ponsim_olt.py
+++ b/voltha/adapters/ponsim_olt/ponsim_olt.py
@@ -494,9 +494,9 @@
         self.adapter_agent.update_device(device)
         self.logical_device_id = ld_initialized.id
 
-        # register ONUS per uni port
-        for port_no in info.uni_ports:
-            vlan_id = port_no
+        # register ONUS
+        for onu in info.onus:
+            vlan_id = onu.uni_port
             self.adapter_agent.child_device_detected(
                 parent_device_id=device.id,
                 parent_port_no=1,
@@ -506,7 +506,8 @@
                     channel_id=vlan_id
                 ),
                 admin_state=AdminState.ENABLED,
-                vlan=vlan_id
+                vlan=vlan_id,
+                serial_number=onu.serial_number
             )
 
         if self.ponsim_comm == 'grpc':