MFC 304270,304273
304270
hyperv/util: Don't reference hn_softc in KVP hn_softc is private data struct. Sponsored by: Microsoft Differential Revision: https://reviews.freebsd.org/D7519
304273
hyperv/util: Factor out helper for IC device_probe DEVMETHOD Sponsored by: Microsoft Differential Revision: https://reviews.freebsd.org/D7530