dnsmasq: Update listeners when interface set changes

dnsmasq does not update its list of listeners with the new
interface object whenver an interface goes up/down and hence
when we free the old interface objects, the interface info in
dnsmasq listeners is lost. This fix makes sure the listenerss
are updated with the new interface object

Change-Id: Ib3204d0d94c28a57f473fc04c5a10a52fc48e754
CRs-Fixed: 586287