MT#62705 fix get_peer_auth_params() $rs

* fix $rs check expression to check for both undef and $rs->value
  as otherwise it fails when $type is neither 'subscirbers' nor
  'peerings'

Change-Id: I59e2c445416d5107a4aa207a9f16552d806df54d
(cherry picked from commit 8037316fe4)

lib/NGCP/Panel/Utils/Preferences.pm

@@ -2768,7 +2768,7 @@ sub get_peer_auth_params {
                 peer_host => $prov_object
             );
         }
-        $prefs->{$attribute} = $rs->first ? $rs->first->value : undef;
+        $prefs->{$attribute} = $rs && $rs->first ? $rs->first->value : undef;
     }
 }