- make pkt0 interface non-persistent. When agent dies, pkt0 interface will
also leave the system, indicating the vrouter that agent is not alive.

Change-Id: Ic24a005e2c6739fd12fe1a42afbaa84cf4ac1b4d
Merge "- make pkt0 interface non-persistent. When agent dies, pkt0 interface will also leave the system, indicating the vrouter that agent is not alive."