Set blank link-local explicitly

Avoid adding ipv6 to evpn interfaces

Related-Prod: PRODX-3456
Change-Id: Ic93ba681cd76cb35e072a821d0be2b33aa04e738
diff --git a/de/heat-templates/scripts/instance_boot.sh b/de/heat-templates/scripts/instance_boot.sh
index acc90f2..14f2f75 100644
--- a/de/heat-templates/scripts/instance_boot.sh
+++ b/de/heat-templates/scripts/instance_boot.sh
@@ -703,6 +703,7 @@
 cat << EOF >> /etc/netplan/60-evpn.yaml
         br$vni:
           dhcp4: false
+          link-local: []
           parameters:
             stp: false
           interfaces: