MFC 295304,295305,295306

MFC 295304,295305,295306

295304
    hyperv/hn: Increase LRO entry count to 128 by default

    hn(4) only has one RX ring currently, so default 8 LRO entries
    are too small.

    Reviewed by:        adrian
    Approved by:        adrian (mentor)
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5166

295305
    hyperv/hn: Move LRO flush to the channel processing rollup

    This significantly increases LRO aggregation ratio when there are
    large amount of connections (improves reception performance a lot).

    Reviewed by:        adrian
    Approved by:        adrian (mentor)
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5167

295306
    hyperv/hn: Add an option to always do transmission scheduling

    It is off by default. This eases more experiment on hn(4).

    Reviewed by:        adrian, Hongjiang Zhang <honzhan microsoft com>
    Approved by:        adrian (mentor)
    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5175

git-svn-id: svn://svn.freebsd.org/base/stable/10@301858 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f