6659 nvlist_free(NULL) is a no-op

@@ -1280,11 +1280,10 @@
                 penext = pe->pe_next;
                 for (ve = pe->pe_vdevs; ve != NULL; ve = venext) {
                         venext = ve->ve_next;
                         for (ce = ve->ve_configs; ce != NULL; ce = cenext) {
                                 cenext = ce->ce_next;
-                                if (ce->ce_config)
                                         nvlist_free(ce->ce_config);
                                 free(ce);
                         }
                         free(ve);
                 }