sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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/arm64 broadcom: Remove unused devclass arguments to DRIVER_MODULE.

bcm2835_systimer: Remove unused variable.

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

Switch to mainstream DTS for Raspberry Pi-B and Pi-2.
This is first step in attempt to make FreeBSD compatible with all variants of
RPi boards.

Reviewed by: gonzo
MFC after: 3 weeks

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.

Stop including fdt_common.h from the arm code when it's unneeded.

Sponsored by: ABT Systems Ltd

RPI-B: Add support for MULTIDELAY

100 cycles per us seems accurate enough, at least it's better than the 200 value
that was used before.

Reviewed by: andrew, imp
Differential Revision: https://reviews.freebsd.org/D8062

Use simple fixed name strings for these timecounters and eventimers which
are tied to fixed pieces of hardware; dynamic string formatting isn't needed.

Stop using machine/fdt.h in the arm kernel code when we don't need it.

Replace many pasted identical definitions of cpu_initclocks() with a common
implementation in arm/machdep.c. Most arm platforms either don't need to
do anything, or just need to call the standard eventtimer init routines.
A generic implementation that does that is now provided via weak linkage.
Any platform that needs to do something different can provide a its own
implementation to override the generic one.

Follow r261352 by updating all drivers which are children of simplebus
to check the status property in their probe routines.

Simplebus used to only instantiate its children whose status="okay"
but that was improper behavior, fixed in r261352. Now that it doesn't
check anymore and probes all its children; the children all have to
do the check because really only the children know how to properly
interpret their status property strings.

Right now all existing drivers only understand "okay" versus something-
that's-not-okay, so they all use the new ofw_bus_status_okay() helper.

Remove #include <machine/frame.h> from all the arm code that doesn't
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.

Fix DELAY() on RPi, the wrong math was making it take twice it should.

Reported by: Alexander <sht@ropnet.ru>
Approved by: adrian (mentor)
Approved by: re (gjb)

Minimal timer period of 100us introduced in r244758 is overkill. While
original 2us are indeed not enough, 3us are working quite well on my tests.
To be more safe set minimal period to 5us and to be even more safe replicate
here from HPET mechanism of rereading counter after programming comparator.

This change allows to handle 30K of short nanosleep() calls per second on
Raspberry Pi instead of just 8K before.

Discussed with: gonzo

MFcalloutng:
Switch eventtimers(9) from using struct bintime to sbintime_t.
Even before this not a single driver really supported full dynamic range of
struct bintime even in theory, not speaking about practical inexpediency.
This change legitimates the status quo and cleans up the code.

Fix event timer on Raspberry Pi

- Disable interrupt when updating compare value in order to
make this operation atomical

- Increase minimum period for event timer. Systimer on BCM2835
is compare timer, so if minimum period is too small it might
be less then fraction of time between "read current value" and
"set compare timer" operations. It means that when timer is armed
actual counter value is more then compare value and it will take
whole cycle (~32sec for 1MHz timer) to fire interrupt.

Submitted by: Daisuke Aoyama <aoyama at peach.ne.jp>

Fix spelling.

remove duplicate semicolons where possible.

Approved by: cperciva
MFC after: 1 week

Add barebone Raspberry Pi port. Supported parts:
- Interrupts controller
- Watchdog
- System timer
- Framebuffer (hardcoded resolution/bpp)