MFC 300576,300644

MFC 300576,300644

300576
    hyperv/vmbus: Free message taskqueue during interrupt teardown

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D6506

300644
    hyperv/vmbus: Check hyperv_dmamem_alloc return value

    Though it is highly unlikely this function would fail w/ BUS_DMA_WAITOK,
    we had better to check its return value; better safe then sorry here.

    MFC after:  1 week
    Sponsored by:       Microsoft OSTC
    Differential Revision:      https://reviews.freebsd.org/D6518

git-svn-id: svn://svn.freebsd.org/base/stable/10@302122 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f