ospf6d: Remove obsolete code

* ospf6_area.c: (ospf6_area_delete) Get rid of unused code that refers
    to a nonexistent function and structure member.
diff --git a/ospf6d/ospf6_area.c b/ospf6d/ospf6_area.c
index bf8dbc3..f4b327e 100644
--- a/ospf6d/ospf6_area.c
+++ b/ospf6d/ospf6_area.c
@@ -203,11 +203,6 @@
   ospf6_route_table_delete (oa->spf_table);
   ospf6_route_table_delete (oa->route_table);
 
-#if 0
-  ospf6_spftree_delete (oa->spf_tree);
-  ospf6_route_table_delete (oa->topology_table);
-#endif /*0*/
-
   THREAD_OFF (oa->thread_spf_calculation);
   THREAD_OFF (oa->thread_route_calculation);