Closes-bug : 1364397
Fix agent crash while updating floating-IP statistics for interface which has become inactive.

Change-Id: I049919046d4009075dab630b8a936e9f62386af9
(cherry picked from commit a49a05e32efef8f78cba6548c747337da2235eb3)
Merge "Closes-bug : 1364397 Fix agent crash while updating floating-IP statistics for interface which has become inactive."