drm/ttm: fix LRU handling in ttm_buffer_object_transfer

We need to set the NO_EVICT flag on the ghost object or otherwise we are
adding it to the LRU.

When it is added to the LRU we can run into a race between destroying
and evicting it again.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>