drm/ttm: cleanup the resource of ghost objects after locking them

Otherwise lockdep will complain about cleaning up the bulk_move.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220907100051.570641-1-christian.koenig@amd.com
Fixes: d91c411c ("drm/ttm: update bulk move object of ghost BO")