vfio/fsl-mc: Use vfio_init/register/unregister_group_dev

fsl-mc already allocates a struct vfio_fsl_mc_device with exactly the same
lifetime as vfio_device, switch to the new API and embed vfio_device in
vfio_fsl_mc_device. While here remove the devm usage for the vdev, this
code is clean and doesn't need devm.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <6-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>