HomeFreeBSD

Avoid panic from ng_uncallout when unpluggin ethernet cable with active

Description

Avoid panic from ng_uncallout when unpluggin ethernet cable with active
PPTP VPN connection.

Submitted by: Michael Zhilin <mizhka@gmail.com>
Reviewed by: ngie
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D7209