vfio: Make vfio_(un)register_notifier accept a vfio_device

All callers have a struct vfio_device trivially available, pass it in
directly and avoid calling the expensive vfio_group_get_from_dev().

Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Jason J. Herne <jjherne@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/1-v4-8045e76bf00b+13d-vfio_mdev_no_group_jgg@nvidia.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>