Remove GRE link flag options from GUI/backend. Keep link1 as it was also used to add an explicit static route, though the GUI previous GUI option name wasn't related to that at all. Updated GUI description to match reality. Ticket #6586
Related issues
Todo #6586: interfaces_gre_edit.php: Checkbox options that set link0, link1, and link2 appear to be no-ops on FreeBSD now
Remove GRE link flag options from GUI/backend. Keep link1 as it was also used to add an explicit static route, though the GUI previous GUI option name wasn't related to that at all. Updated GUI description to match reality. Ticket #6586