MFC 297802,297803(297481),297804

MFC 297802,297803(297481),297804

297802
    hyperv: Identify Hyper-V features and recommends properly

    Features bits will be used to detect devices, e.g. timers, which
    do not have corresponding event channels.

    Submitted by:       Jun Su <junsu microsoft com>
    Reviewed by:        sephe, Dexuan Cui <decui microsoft com>
    Rearranged by:      sephe
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC

279803(297481)
    hyperv: Register Hyper-V timer early enough for TSC freq calibration

    The i8254 simulation in Hyper-V is kinda broken and is not available
    in Generation 2 Hyper-V VMs, so Hyper-V timer must be registered early
    enough so that it can be used to do the TSC freq calibration.

    This fixes the notorious warning like this:
    calcru: runtime went backwards from 50 usec to 25 usec for pid 0 (kernel)

    Submitted by:       Dexuan Cui <decui microsoft com>
    Reviewed by:        kib, sephe
    Tested by:  kib, sephe
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5778

    =================

    hyperv: Resurrect r297481

    This time we make sure that the TIME_REF_COUNT MSR exists.

    Submitted by:       Jun Su <junsu microsoft com>
    Reviewed by:        sephe, Dexuan Cui <decui microsoft com>
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC

297804
    hyperv: Declare hyperv_{features,recommends} properly

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC

git-svn-id: svn://svn.freebsd.org/base/stable/10@301942 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f