VOL-3121 -  Separated out logical ports from logical agent.

Similar to flows/groups/meters.
Also modified device_route tests to generate unique port IDs (`.OfpPort.PortNo`s) across all UNI ports withing each test, i.e. within an OLT.
Also replaced logicalPortsNo map & associated NNI vs UNI logic with root device checks.

Change-Id: Ib0cecbf7d4f8d509ce7c989b9ccf697c8b0d17d6
diff --git a/rw_core/core/device/agent_group.go b/rw_core/core/device/agent_group.go
index 18ac83a..cb9557c 100644
--- a/rw_core/core/device/agent_group.go
+++ b/rw_core/core/device/agent_group.go
@@ -22,7 +22,7 @@
 
 // listDeviceGroups returns logical device flow groups
 func (agent *Agent) listDeviceGroups() map[uint32]*ofp.OfpGroupEntry {
-	groupIDs := agent.groupLoader.List()
+	groupIDs := agent.groupLoader.ListIDs()
 	groups := make(map[uint32]*ofp.OfpGroupEntry, len(groupIDs))
 	for groupID := range groupIDs {
 		if groupHandle, have := agent.groupLoader.Lock(groupID); have {