hyperv/storvsc: Don't use timedwait.

The timeout is unnecessary.

Reviewed by:    jhb
Sponsored by:   Microsoft
Differential Revision:  https://reviews.freebsd.org/D8656

hyperv/storvsc: Fix the SCSI disk attachment issue.

On pre-WS2016 Hyper-V, if the only LUNs > 7 are used, then all disks
fails to attach.  Mainly because those versions of Hyper-V do not set
SRB_STATUS properly and deliver junky INQUERY responses.

Submitted by:   Hongjiang Zhang <honzhan microsoft com>
Reported by:    Hongxiong Xian <v-hoxian microsoft com>
Sponsored by:   Microsoft
Differential Revision:  https://reviews.freebsd.org/D8724

hyperv/storvsc: Minor style changes; no functional changes.

Reported by:    rpokala
Sponsored by:   Microsoft