MFC 297180,297181,297182

MFC 297180,297181,297182

297180
    hyperv/hn: Reduce TCP segment aggregation limit for multiple RX rings

    This mainly used to improve ACK timeliness when multiple RX rings
    are enabled.

    This value gives the best performance in both Azure and Hyper-V
    environment, w/ both 10Ge and 40Ge using non-{INVARIANTS,WITNESS}
    kernel.

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5691

297181
    hyperv/hn: Factor out hn_set_lro_lenlim()

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5692

297182
    hyperv/hn: When short of mbufs on the RX path, don't spam the console.

    Instead, increase the IQDROPS counter.

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D5693

git-svn-id: svn://svn.freebsd.org/base/stable/10@301947 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f