zone: use just one free function

src/knot/ctl/knotc_main.c

@@ -693,7 +693,7 @@ static int cmd_checkzone(int argc, char *argv[], unsigned flags)
log_zone_info("Zone %s OK.\n", zone->name);
rem_node((node_t *)zone);
-		zone_deep_free(&z);
+		zone_free(&z);
knot_zload_close(l);
}