AETHER-3189 Update ids to be dns compliant:

Change-Id: Ic03b51c62fb205a5505a15e743f93b0057f9b93b
diff --git a/config-models/aether-2.0.x/files/yang/onf-priority-traffic-rule.yang b/config-models/aether-2.0.x/files/yang/onf-priority-traffic-rule.yang
index 4c8db55..2706eba 100755
--- a/config-models/aether-2.0.x/files/yang/onf-priority-traffic-rule.yang
+++ b/config-models/aether-2.0.x/files/yang/onf-priority-traffic-rule.yang
@@ -5,7 +5,6 @@
 submodule onf-priority-traffic-rule {
   belongs-to onf-enterprise { prefix ent; }
 
-  import ietf-yang-types{ prefix yg; }
   import onf-aether-types{ prefix at; }
   include onf-device;
   include onf-traffic-class;
@@ -23,9 +22,7 @@
   }
 
   typedef priority-traffic-rule-id {
-        type yg:yang-identifier {
-            length 1..32;
-        }
+    type at:aether-identifier;
     description "The typedef for priority traffic rule id";
   }