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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

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.

Some devices come with the same name as TI devices, so we can't rely on the
"probe" method of those drivers to mean we're on e TI SoC. Introduce a new
function, ti_soc_is_supported(), and use it to be sure we're really a TI
system.

PR: 222250

The only remaining offender that used ti_chip() without checking for
compatibility first was the gpio code, so change that, and re-assert
that the TI chip is a known chip

Don't panic if it's not a TI chip, this code can be called when it is not.

Guess the TI chip based on the PLATFORM infos, instead of relying on the
kernel config file.

Start removing the omap3 support. In base it was only ever a header and a
few changes to drivers, no kernel config was added. As the SoCs are quite
old and the code is unmaintained start the process of removing support by
deleting the header file and code that depends on it along with the macro
SOC_OMAP3. Other Ti SoCs shouldn't be affected, other than for us to have
less code to maintain.

Differential Revision: https://reviews.freebsd.org/D936
Reviewed by: rpaulo, loos

- Identify more devices for OMAP4 SoC (up to OMAP4470)
- Whitespace fixes

Merging of projects/armv6, part 10

- Support for Texas Instruments SoCs:
- AM335x
- OMAP4

- Kernel configs, DTS for Beaglebone and Pandaboard

Submitted by: Ben Gray, Damjan Marion