MFC r294557:

hyperv/stor: Verify returned inquiry data before further dispatching

Windows 10 and Window 2016 will return all zero inquiry data for
non-existing slots. If we dispatched them, then a lot of useless
(0 sized) disks would be created. So we verify the returned inquiry
data (valid type, non-empty vendor/product/revision etc.), before
further dispatching.

Minor white space cleanup and wording fix.

Submitted by: Hongjiang Zhang <honzhan microsoft com>
Reviewed by: adrian, sephe, Jun Su <junsu microsoft com>
Approved by: adrian (mentor)
Modified by: sephe
Sponsored by: Microsoft OSTC
Differential Revision: https://reviews.freebsd.org/D4928