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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

fdt_slicer: bump to SI_ORDER_THIRD following r347183

r347183 bumped GEOM classes to SI_ORDER_SECOND to resolve a race between
them and the initialization of devsoftc.mtx in devinit, but missed this
dependency on g_flashmap that may now lose the race against GEOM
classes/g_init.

There's a great comment that describes the situation that has also been
updated with the new ordering of GEOM classes.

Reported by: bdragon
MFC after: 4 days

fdt: Explicitly mark fdt_slicer as dependent on geom_flashmap

Without this dependency relationship, the linker doesn't find the
flash_register_slicer() function, so kldload fails to load fdt_slicer.ko.

Discussed with: ian@

Add support to fdt_slicer for the new style partition data documented in
devicetree/bindings/mtd/partition.txt.

In the old style, all the children of the device node which did not have a
compatible property were the partitions. In the new style, there is a child
node of the device which has a compatible string of "fixed-partitions", and
its children are the individual partitions.

Also, support the read-only property by setting the corresponding slice flag.

Child nodes with a compatible property are not slices, according to the
devicetree/bindings/mtd/partitions.txt document, so just ignore them.

Rename some functions and variables to have shorter names, which allows
unwrapping multiple lines of code. Also, convert some short multiline
comments into single-line comments. Change old-school FALSE to false.

All in all, no functional changes, it's just more compact and readable.

Make it possible to load fdt_slicer as a module (unloading works too fwiw).

Clean up OF_getprop_alloc API

OF_getprop_alloc takes element size argument and returns number of
elements in the property. There are valid use cases for such behavior
but mostly API consumers pass 1 as element size to get string
properties. What API users would expect from OF_getprop_alloc is to be
a combination of malloc + OF_getprop with the same semantic of return
value. This patch modifies API signature to match these expectations.

For the valid use cases with element size != 1 and to reduce
modification scope new OF_getprop_alloc_multi function has been
introduced that behaves the same way OF_getprop_alloc behaved prior to
this patch.

Reviewed by: ian, manu
Differential Revision: https://reviews.freebsd.org/D14850

sys/dev: 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.

- Allow different slicers for different flash types to be registered
with geom_flashmap(4) and teach it about MMC for slicing enhanced
user data area partitions. The FDT slicer still is the default for
CFI, NAND and SPI flash on FDT-enabled platforms.
- In addition to a device_t, also pass the name of the GEOM provider
in question to the slicers as a single device may provide more than
provider.
- Build a geom_flashmap.ko.
- Use MODULE_VERSION() so other modules can depend on geom_flashmap(4).
- Remove redundant/superfluous GEOM routines that either do nothing
or provide/just call default GEOM (slice) functionality.
- Trim/adjust includes

Submitted by: jhibbits (RouterBoard bits)
Reviewed by: jhibbits

Create a RouterBoard platform and use it to create a flash map

Summary:
The RouterBoard uses a predefined partition map which doesn't exist in the fdt.
This change allows overriding the fdt slicer with a custom slicer, and uses this
custom slicer to define the flash map on the RouterBoard RB800.
D3305 converts the mpc85xx platform into a base class, so that systems based on
the mpc85xx platform can add their own overrides. This change builds on D3305,
and creates a RouterBoard (RB800) platform to initialize the slicer override.

Reviewed By: nwhitehorn, imp
Differential Revision: https://reviews.freebsd.org/D3345

Remove all the instances of '#undef DEBUG' from kernel.

Suggested by: rpaulo
Approved by: adrian (mentor)

Add a new geom class which allows to divide NAND Flash chip
into partitions.

Partitions are created based on data in dts file which are
extracted and interpreted by slicer.

Obtained from: Semihalf
Supported by: FreeBSD Foundation, Juniper Networks