Fix uninitialized vrouter params

Issue:
------
uninitialized variable results in bad calculation of number
of MPLS labels for multicast

Fix:
----
initialize vrouter params to 0, handle case if
vrouter_max_labels is lesser than fixed unicast range.

Conflicts:
	src/vnsw/agent/cmn/agent.cc

Closes-Bug: 1535735
Change-Id: Id4a7b74f12728e78dcb5b8b24d0848e560ff0138
(cherry picked from commit eb0488b)

src/vnsw/agent/controller/controller_init.cc

@@ -92,7 +92,7 @@ void VNController::SetAgentMcastLabelRange(uint8_t idx) {
     //         split remaining unicast label for both control
     //         node
     //  Remaining label would be used for unicast mpls label
-    if (agent_->vrouter_max_labels() == 0) {
+    if (agent_->vrouter_max_labels() <=  MIN_UNICAST_LABEL_RANGE) {
         str << 0 << "-" << 0;
         fabric_multicast_label_range_[idx].start = 0;
         fabric_multicast_label_range_[idx].end = 0;