On deactivation of L2, vxlan id in vm interface gets reset.
On activation retrieve it from VN if l2 is active.

https://bugs.launchpad.net/bugs/1356716

Change-Id: Idb44911a2c8a54b3943c44bced2971763f3c364b
Merge "On deactivation of L2, vxlan id in vm interface gets reset. On activation retrieve it from VN if l2 is active."