Make DPDK vRouter dependent on liburcu2

There are works undergoing that make the DPDK vRouter to be dependent on newer
version of liburcu. The package has to take this into account.

Change-Id: Ie961de8e3a9125feef518795b43b4bde03a54e5f
Related-Bug: #1537206

debian/contrail-vrouter-dpdk/debian/control

@@ -6,7 +6,7 @@ Priority: optional
 Package: contrail-vrouter-dpdk
 Architecture: all
 Depends: contrail-vrouter-utils (= ${binary:Version}),
-         contrail-dpdk-kernel-modules-dkms, liburcu1, ${misc:Depends}
+         contrail-dpdk-kernel-modules-dkms, liburcu2, ${misc:Depends}
 Provides: contrail-vrouter
 Description: OpenContrail VRouter - DPDK version
  OpenContrail is a network virtualization solution that provides an overlay