The function adf_sriov_prepare_restart() is used in adf_sriov.c to stop
and shutdown a device preserving its configuration.

Since this function will be re-used by the logic that allows to
reconfigure the device through sysfs, move it to adf_init.c and rename
it as adf_dev_shutdown_cache_cfg();
Signed-off-by: NGiovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: NAdam Guerin <adam.guerin@intel.com>
Reviewed-by: NFiona Trahe <fiona.trahe@intel.com>
Reviewed-by: NWojciech Ziemba <wojciech.ziemba@intel.com>
Reviewed-by: NVladis Dronov <vdronov@redhat.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>