drm/i915/gvt: convert to use vfio_register_emulated_iommu_dev

This is straightforward conversion, the intel_vgpu already has a pointer
to the vfio_dev, which can be replaced with the embedded structure and
we can replace all the mdev_get_drvdata() with a simple container_of().

Based on an patch from Jason Gunthorpe.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20220411141403.86980-29-hch@lst.deReviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>

drivers/gpu/drm/i915/gvt/gvt.h

@@ -211,7 +211,7 @@ struct intel_vgpu {
 
 	u32 scan_nonprivbb;
 
-	struct mdev_device *mdev;
+	struct vfio_device vfio_device;
 	struct vfio_region *region;
 	int num_regions;
 	struct eventfd_ctx *intx_trigger;