Remove requirement for setting port type when setting as inactive

[rowanthorpe]

As far as I understand it this is just a convenience improvement I'm suggesting....

A switch can start (e.g. after an snmp update) with many/all ports listed as Type = Unset/Unknown, but when editing the port to untick it as active I can't save it unless I set the port type to something other than Unset/Unknown (obviously there is a hard restriction in place that no updates to the port can be saved with type = Unset/Unknown). This leads to the slightly non-intuitive situation where active ports can be Unset/Unknown but inactive ports can't. When router-admins are in a real hurry and see that they need to also set each port-type in order to mark it inactive, they instead just leave it as active, which is probably less desirable(?). I suggest being able to set a port to inactive without needing to also categorise it yet.