Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

Similar commit in current:
(cherry picked from commit 95ee2897e98f)

No functional change intended, but noticed that we could add const here
while adding linuxkpi support for virtio.

Reviewed By:	bryanv, imp
Differential Revision: https://reviews.freebsd.org/D32370

(cherry picked from commit 6c4f95161d6e38ba3fd50ca1cceee3110cbfa02e)

Definitions inside usr.sbin/bhyve/virtio.h are thrown away.
Definitions in sys/dev/virtio are used instead.

This reduces code duplication.

Sponsored by:	The FreeBSD Foundation
Reviewed by:	grehan
Approved by:	philip (mentor)
Differential Revision:	https://reviews.freebsd.org/D29084

(cherry picked from commit 54ac6f721efccdba5a09aa9f38be0a1c4ef6cf14)

Rather than have every device register itself for both virtio_pci and
virtio_mmio, provide a VIRTIO_DRIVER_MODULE wrapper to declare both,
merge VIRTIO_SIMPLE_PNPTABLE with VIRTIO_SIMPLE_PNPINFO and make the
latter register for both buses. This also has the benefit of abstracting
away the available transports and their names.

Reviewed by:	bryanv
Differential Revision:	https://reviews.freebsd.org/D28073

Reviewed by: grehan (mentor)
Differential Revision: https://reviews.freebsd.org/D27898

Use the existing legacy PCI driver as the basis for shared code
between the legacy and modern PCI drivers. The existing virtio_pci
kernel module will contain both the legacy and modern drivers.

Changes to the virtqueue and each device driver (network, block, etc)
for V1 support come in later commits.

Update the MMIO driver to reflect the VirtIO bus method changes, but
the modern compliance can be improved on later.

Note that the modern PCI driver requires bus_map_resource() to be
implemented, which is not the case on all archs.

The hw.virtio.pci.transitional tunable default value is zero so
transitional devices will continue to be driven via the legacy
driver.

Reviewed by: grehan (mentor)
Differential Revision: https://reviews.freebsd.org/D27856

Register MODULE_PNP_INFO for virtio devices using the newbus PNP information
provided by the previous commit.  Matching can be quite simple; existing
probe routines only matched on bus (implicit) and device_type.  The same
matching criteria are retained exactly, but is now also available to
devmatch(8).

Reviewed by:	bryanv, markj; imp (earlier version)
Differential Revision:	https://reviews.freebsd.org/D20407

Expose the same fields and widths from both vtio buses, even though they
don't quite line up; several virtio drivers can attach to both buses,
and sharing a PNP info table for both seems more convenient.

In practice, I doubt any virtio driver really needs to match on anything
other than bus and device_type (eliminating the unused entries for
vtmmio), and also in practice device_type is << 2^16 (so far, values
range from 1 to 20).  So it might be fine to only expose a 16-bit
device_type for PNP purposes.  On the other hand, I don't see much harm
in overkill here.

Reviewed by:	bryanv, markj (earlier version)
Differential Revision:	https://reviews.freebsd.org/D20406

VirtIO buses (PCI, MMIO) can provide a generation field so a driver
can ensure either a 64-bit or array read was stable.

MFC after:	2 weeks

Mainly focus on files that use BSD 3-Clause license.

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.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.