set only if parameter doesnt exist

git-svn-id: svn://svn.dd-wrt.com/DD-WRT@21662 52c4871e-980c-0410-b1e0-e73912ce01f8
update range for Maximum Ports as it is now possible to raise it to 65536

git-svn-id: svn://svn.dd-wrt.com/DD-WRT@21663 52c4871e-980c-0410-b1e0-e73912ce01f8