Fix mdns listen option

In case when Designate is setup with powerdns and designate-mdns
servers are supermasters for powerdns, it is required to set port
for mdns to not standard value - 53

Change-Id: I9774a709cb0dd24caa45964bf93d9bb28f8072b9
Related-Prod: https://mirantis.jira.com/browse/PROD-23369
diff --git a/designate/files/queens/designate.conf.Debian b/designate/files/queens/designate.conf.Debian
index 47630b6..906bf0d 100644
--- a/designate/files/queens/designate.conf.Debian
+++ b/designate/files/queens/designate.conf.Debian
@@ -812,7 +812,7 @@
 
 # mDNS host:port pairs to listen on (list value)
 #listen = 0.0.0.0:5354
-
+listen = {{ server.mdns.address }}:{{ server.mdns.port }}
 
 # mDNS TCP Backlog (integer value)
 #tcp_backlog = 100