5047 don't use atomic_*_nv if you discard the return value

@@ -1111,11 +1111,11 @@
 {
         if (atomic_dec_uint_nv(&tnp->tn_refs) == 0) {
                 if (tnp->tn_tsp != NULL)
                         trill_sock_unref(tnp->tn_tsp);
                 trill_node_free(tnp);
-                (void) atomic_dec_uint_nv(&tip->ti_nodecount);
+                atomic_dec_uint(&tip->ti_nodecount);
         }
 }
 
 static trill_node_t *
 trill_node_lookup(trill_inst_t *tip, uint16_t nick)