sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

cgem: support SGMII PHY connection mode

As the PolarFire SoC needs SGMII to connect the PHY, check the
'phy-mode' property of device tree node for ethernet and act on it
appropriately.

Add the compatible strings for the PolarFire SoC device tree.
'microchip,mpfs-mss-gem" is not officially documented but has been
observed in the available firmware for this platform, so it is included
for now.

Also, fix a typo in if_cgem_hw.h.

Reviewed by: mhorne
MFC after: 1 week
Sponsored by: Conclusive Engineering
Differential Revision: https://reviews.freebsd.org/D34764

cgem: add 64-bit support

Add 64-bit address support to Cadence CGEM Ethernet driver for use in
other SoCs such as the Zynq UltraScale+ and SiFive HighFive Unleashed.

Reviewed by: philip, 0mp (manpages)
Differential Revision: https://reviews.freebsd.org/D24304

Cadence GEM ethernet driver style clean-up, no functional changes.

This is mostly indentation whitespace, and reflowing a few multiline
comments. This gets a bunch of minor stuff out of the way so that the diffs
for style don't clutter up the diffs for some upcoming functional changes.

Submitted by: Thomas Skibo
Differential Revision: https://reviews.freebsd.org/D24226

sys/dev: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Fixes and enhancements for the if_cgem driver...

- miibus fixes as suggested by Yonghyeon Pyun.
- enable VLAN MTU support.
- fix a few WITNESS complaints in cgem_attach().
- have cgem_attach() properly init the ifnet struct before calling
mii_attach() to fix panic when using e1000phy.
- fix ethernet address changing.
- fix transmit queue overflow handling.
- tweak receive queue handling to reduce receive overflows.
- bring out MAC statistic counters to sysctls.
- add e1000phy to config file.
- implement receive hang work-around described in reference guide.
- change device name from if_cgem to cgem to be consistent with other
interfaces.

Submitted by: Thomas Skibo <ThomasSkibo@sbcglobal.net>
Reviewed by: wkoszek, Yonghyeon PYUN <pyunyh@gmail.com>

Bring copyright changes with the agreement of Thomas Skibo.

Communication on src-commiters, Sat, 27 Apr 2013 22:09:06 -0700,
Subject was: "Re: svn commit: r249997"

As I'm here, fix the style main block comments in files' headers.

Add Xilinx Zynq ARM/FPGA SoC support to FreeBSD/arm port.

Submitted by: Thomas Skibo <ThomasSkibo (at) sbcglobal.net>
Reviewed by: wkoszek, freebsd-arm@ (no objections raised)