MFC 316520

MFC 316520

    hyperv/hn: Fixat RNDIS rxfilter after the successful RNDIS init.

    Under certain conditions on certain versions of Hyper-V, the RNDIS
    rxfilter is _not_ zero on the hypervisor side after the successful
    RNDIS initialization, which breaks the assumption of any following
    code (well, it breaks the RNDIS API contract actually).  Clear the
    RNDIS rxfilter explicitly, drain packets sneaking through, and drain
    the interrupt taskqueues scheduled due to the stealth packets.

    Reported by:    dexuan@
    Sponsored by:   Microsoft
    Differential Revision:  https://reviews.freebsd.org/D10230

git-svn-id: svn://svn.freebsd.org/base/stable/10@316672 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f