MFC 309346,309348

309346
hyperv/hn: Add HN_DEBUG kernel option.

If bufring is used for per-TX ring descs, don't update "available"
counter, which is only used to help debugging.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8674

309348
hyperv/hn: Don't hold txdesc, if no BPFs are attached.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8675

MFC 308163

hyperv/hn: Rename cleaned up file.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8390

MFC 308018,308116

308018
hyeprv/hn: Rename cleaned up RNDIS header file.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8360

308116
hyperv/hn: Rename cleaned up RNDIS source file.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8361

MFC 308011,308012

308011
hyperv/hn: Rename cleaned up NVS header file.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8353

308012
hyperv/hn: Rename cleaned up NVS source file.

Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D8354

MFC 302617-302621,302623,302629-302631

302617
hyperv/vmbus: Flatten channel message response processing.

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6914

302618
hyperv/vmbus: Avoid tx_evtflags setting code duplication.

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6915

302619
hyperv/vmbus: Busdma-fy Hypercall signal event input parameter.

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6916

302620
hyperv: Nuke unused stuffs

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6917

302621
hyperv/vmbus: Don't be oversmart in default cpu selection.

Pin the channel to cpu0 by default. Drivers having special channel-cpu
mapping requirement should call vmbus_channel_cpu_{set,rr}() themselves.

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6918

302623
hyperv/vmbus: Minor renaming

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6919

302629
hyperv/vmbus: Rework vmbus version accessing.

Instead of global variable, vmbus version is accessed through
a vmbus DEVMETHOD now.

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6953

302630
hyperv/vmbus: Move GPADL index into vmbus_softc

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6954

302631
hyperv/vmbus: Move channel list to vmbus_softc

Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D6956

MFC r284969:
r284969 (by lwhsu):

- Fix `make depend` in sys/modules

Differential Revision: https://reviews.freebsd.org/D2951
Approved by: delphij

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix make depend, apply a bit of style.

Approved by: re (marius)
Reviewed by: grehan

Import Hyper-V paravirtualized drivers from projects/hyperv
branch into head.

Approved by: re@ (hrs)
Obtained from: Microsoft, NetApp, and Citrix.

Latest update from Microsoft.

Obtained from: Microsoft Hyper-v dev team

Microsoft have changed their policy on how the hyper-v code will
be pulled into FreeBSD. From now, FreeBSD will be considered the
upstream repo.

First step: move the drivers away from the contrib area and into
the base system.

A follow-on commit will include the drivers in the amd64 GENERIC kernel.

make glue to hook up the hyperv kmods to the build.

Modified from the original Microsoft versions to pull
code/headers in from the sys/contrib/dev directory.