hyperv/storvsc: Fix the blkvsc disk attachment issues.

- The original 'disengage' ATA controller model does not work properly
  for all possible disk configurations.  Use the newly added ATA disk
  veto eventhandler to fit into all possible disk configuration.
- If the 'invalid LUN' happens on blkvsc controllers, return
  CAM_DEV_NOT_THERE so that CAM will not destroy attached disks under
  the blkvsc controllers.

Submitted by:   Hongjiang Zhang <honzhan microsoft com>
Discussed with: mav
Sponsored by:   Microsoft
Differential Revision:  https://reviews.freebsd.org/D7693