Fixed displaying of A6 Record

UI was modified to reflect changes in #2309.

Now it uses a6_part_data attribute instead of a6record. This fixes displaying of values in a table and modification of existing A6 record.

https://fedorahosted.org/freeipa/ticket/2367

install/ui/dns.js

@@ -569,9 +569,9 @@ IPA.dns.get_record_metadata = function() {
         {
             name: 'a6record',
             attributes: [
-                'a6record'
+                'a6_part_data'
             ],
-            columns: ['a6record']
+            columns: ['a6_part_data']
         },
         {
             name: 'afsdbrecord',