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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

arm: clean up empty lines in .c and .h files

sys/arm: 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.

Convert the Zynq SoC support to the new routines for static device mapping.

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)