MFC 303822-303824

MFC 303822-303824

303822
    hyperv/ic: Remove never used second parameter of hv_negotiate_version()

    Sponsored by:   Microsoft
    Differential Revision:  https://reviews.freebsd.org/D7422

303823
    hyperv/ic: Expose the receive buffer length for callers to use.

    Sponsored by:   Microsoft
    Differential Revision:  https://reviews.freebsd.org/D7423

303824
    hyperv/ic: Pass the channel callback to hv_util_attach()

    The saved channel callback in util softc is actually never used.

    Sponsored by:   Microsoft
    Differential Revision:  https://reviews.freebsd.org/D7424

git-svn-id: svn://svn.freebsd.org/base/stable/10@307160 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f