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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Add mode selection to iMX6 IPU driver

- Configure ipu1_di0 tob e sourced from the VIDEO_PLL(PLL5) and hardcode
frequency to (455000000/3)Mhz. This value, further divided, can yield
frequencies close enough to support 1080p, 720p, 1024x768, and 640x480
modes. This is not ideal but it's an improvement comparing to the only
hardcoded 1024x768 mode.

- Fix memory leaks if attach method failed
- Print EDID when -v passed to the kernel

Add a SPI driver for imx5 and imx6.

It can be compiled into the kernel with "device imx_spi" or loaded as a
module, which is also named "imx_spi".

Adjust whitespace of things added in the past couple years to match the
original style of the file. No functional changes.

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.

Add an ahci driver for imx6.

This was submitted by Rogiel Sulzbach (thank you!) but has a few last-minute
changes by me, mostly where the code interfaces to my still-utterly-deficient
imx6_ccm clocks implementation. So blame me for any mistakes.

Submitted by: Rogiel Sulzbach <rogiel@rogiel.com>
Differential Revision: https://reviews.freebsd.org/D11177

Add a driver for the imx6 EPIT timer that can be used as the system
timecounter instead of the GPT timer, freeing up the more flexible GPT
hardware for other uses. The EPIT driver is a standard (always in the
kernel) driver, and the existing GPT driver is now optional and included
only if you ask for device imx_gpt.

Add CCM functions to enable HDMI framer and IPU units (video controller)

Reviewed by: andrew, ian
Differential Revision: https://reviews.freebsd.org/D4168

Replace magic numbers for CCGRx registers with more descriptive names

Add the code necessary to run the imx6 chip at its lowest clock/power
operating point (396MHz/950mV).

Add support for audio transmitting, include drivers for:
o Digital Audio Multiplexer (AUDMUX)
o Smart Direct Memory Access Controller (SDMA)
o Synchronous Serial Interface (SSI)

Disable by default as it depends on SDMA firmware.

Sponsored by: Machdep, Inc.

Add a missing clock register definition.

Initialize the Low Power Mode bits to keep the ARM cores running during WFI.

Add stubbed-out imx6 support for clocks and power management. This
contains little more than a few stub functions required to keep the
linker happy, but it's enough to let early imx6 development proceed.