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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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: clean up empty lines in .c and .h files

Kill off dummy kbd drivers

As far as I can tell, these are an artifact of times when linker sets
couldn't be empty, otherwise the kernel build would fail due to unresolved
symbols. hselasky fixed this in r268138, and I've audited the kbd portions
to make sure nothing would blow up due to the empty linker set and
successfully compiled+ran a kernel with no keyboard support at all.

Kill them off now since they're no longer required.

MFC after: 1 week

[ofw] fix errneous checks for OF_finddevice(9) return value

OF_finddevices returns ((phandle_t)-1) in case of failure. Some code
in existing drivers checked return value to be equal to 0 or
less/equal to 0 which is also wrong because phandle_t is unsigned
type. Most of these checks were for negative cases that were never
triggered so trhere was no impact on functionality.

Reviewed by: nwhitehorn
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D14645

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.

Use the correct OF_getencprop over OF_getprop + fdt32_to_cpu to read
integer data from the device tree.

Sponsored by: ABT Systems Ltd

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

Sponsored by: ABT Systems Ltd

Use the modern spelling of ofw_bus_node_is_compatible in sys/arm.

Sponsored by: ABT Systems Ltd

ARM: Remove unused includes.

MFC after: 1 week

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.

AM335x LCD controller driver with syscons support

Limitations:
- Raster mode only
- 24 and 32 bpp only