MFC 296293,296296,296297,296305

MFC 296293,296296,296297,296305

296293
    hyperv/hn: Pass channel to hv_nv_on_receive_completion()

    While I'm here, staticize this function.

    Submitted by:       Hongjiang Zhang <honzhan microsoft com>
    Modified by:        sephe
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC

296296
    hyperv/hn: Make read buffer per-channel

    Submitted by:       Hongjiang Zhang <honzhan microsoft com>
    Reorganized by:     sephe
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC

296297
    hyperv/hn: Fix typo in comment

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC

296305
    hyperv/hn: Make # of rings configurable

    And since the host may not being able to allocate the # of rings
    requested by us, save the # of rings allocated by the host in the
    ring_inuse counters; use ring_inuse counters for run time operation.

    This paves the way for the upcoming vRSS support.

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC

git-svn-id: svn://svn.freebsd.org/base/stable/10@301918 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f