spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

linsysfs(4): Reimplement listnics() using ifAPI

Handle if arrival/departure events and VNETs.

Differential Revision: https://reviews.freebsd.org/D38901
MFC after: 1 month
XMFC with: ifAPI, pseudofs

linsysfs(4): Reimplement listnics() using ifAPI

Handle if arrival/departure events.

Reviewed by: melifaro (early version)
Differential Revision: https://reviews.freebsd.org/D38901
MFC after: 1 month
XMFC with: ifAPI