net: remove IFEF_NO_LINK_STATE_CHANGE

This flag was only set for virtual interfaces.
All virtual interfaces have a means of knowing if they are going to work
or not and as such now support link state changes.

If we want this flag back, it should be used as an indicator that
the interfaces does not support link state changes that userland can use
so it can make a decision on what to do when the link state is UNKNOWN.

(roy)