vrrpd: don't update interface addrs on ifup

vrrpd: don't update interface addrs on ifup

Updating interface addresses on autoconfigured VRRP instances when we
receive notification that an interface is up will cause us to delete
that VRRP instance because Zebra deletes all interface addresses when an
interfaces goes down so when it comes back up it has no addresses which
causes us to delete the instance, then Zebra subsequently sends us the
addresses which causes the instance to get recreated, however in a
non-owner scenario this will merely cause us to start in Backup, wait a
while, transition to Master, protodown off our interface, get an
interface up notification, delete all our ip addresses, destroy
ourselves, receive address notifications, recreate ourselves, reenter
Backup and cycle through it all over again.

So we just have to assume that no addresses went away since this
interface was last up.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>