hyperv/hn: Log a warning for RESET_CMPLT.

RESET is not used by the hn(4) at all, and RESET_CMPLT does not even
have a rid to match with the pending requests. So, let's put it
onto an independent switch branch and log a warning about it.

MFC after: 1 week
Sponsored by: Microsoft
Differential Revision: https://reviews.freebsd.org/D7602