MFC 297815,297841,297908,297913
297815
hyperv: Typo Noticed by: kib MFC after: 1 week Sponsored by: Microsoft OSTC
297841
hyperv: Replace 0 w/ NULL Submitted by: pfg MFC after: 1 week Sponsored by: Microsoft OSTC
297908
hyperv/vmbus: Merge duplicated version check for events Submitted by: Jun Su <junsu microsoft com> Reviewed by: sephe MFC after: 1 week Sponsored by: Microsoft OSTC Differential Revision: https://reviews.freebsd.org/D5911
297913
hyperv: device_get_softc does not return NULL MFC after: 1 week Sponsored by: Microsoft OSTC