Revert r366857.

r366857 created a number of problems, tearing down interfaces too
early in shutdown. This resulted in:

• hung ssh sessions when shutting down or rebooting remotely using shutdown (I've used exec shutdown, for years, as apposed to simply shutdown).

• NFS mounted filesystems "disappear" prior to unmount.

• dhclient attached to a VLAN on an interface who's parent interface has already shut down prints errors.

The path forward is to teach lagg(4) and vlan(4) about WOL.

PR: 251531, 251540
PR: 158734, 109980 are broken again
Reported by: jhb, emaste, jtl, Helge Oldach<freebsd_oldach.net>

		Martin Birgmeier <d8zNeCFG_aon.at>

MFC after: Immediately
Discussion at: https://reviews.freebsd.org/D27459