[FS#74] Sysupgrade locks you out if no interfaces are static

[LEDE Bugs]

The following task is now closed:

FS#74 - Sysupgrade locks you out if no interfaces are static
User who did this - Jo-Philipp Wich (jow-)

Reason for closing: Won't implement
Additional comments about closing: No way to cover any possible use case and access through failsafe mechanisms or IPv6 LL is always a fallback possibility.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=74