umb: Introduce the USB umb(4) network driver
This includes the port of a driver originally from OpenBSD, later
ported to NetBSD by the author:
- The umb(4) kernel driver
- The umbctl(8) companion tool
This driver supports USB network devices implementing the
Mobile Broadband Interface Model (MBIM), often found in modern
(internal) USB models for 4G/LTE mobile broadband access.
It is currently limited to IPv4.
umbctl has to be used to display or set MBIM cellular modem
interface parameters (4G/LTE).
Differential Revision: https://reviews.freebsd.org/D48167
Approved by: adrian, zlei
Sponsored by: FreeBSD Foundation
PR: kern/263783
Submitted by: Pierre Pronchery <khorben@defora.org>