[PATCH] drm/i915/gvt: Add missing vfio_unregister_group_dev() call

[Tian, Kevin]

> From: Jason Gunthorpe
> Sent: Friday, September 30, 2022 1:49 AM
> 
> When converting to directly create the vfio_device the mdev driver has to
> put a vfio_register_emulated_iommu_dev() in the probe() and a pairing
> vfio_unregister_group_dev() in the remove.
> 
> This was missed for gvt, add it.
> 
> Cc: stable at vger.kernel.org
> Fixes: 978cf586ac35 ("drm/i915/gvt: convert to use
> vfio_register_emulated_iommu_dev")
> Reported-by: Alex Williamson <alex.williamson at redhat.com>
> Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>

Reviewed-by: Kevin Tian <kevin.tian at intel.com>