Implement amba's own vfio_device_ops.

Remove vfio_platform_probe/remove_common() given no user now.
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20220921104401.38898-13-kevin.tian@intel.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>