drm/ttm: once more fix ttm_bo_bulk_move_lru_tail

While cutting the lists we sometimes accidentally added a list_head from
the stack to the LRUs, effectively corrupting the list.

Remove the list cutting and use explicit list manipulation instead.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-and-Tested: Huang Rui <ray.huang@amd.com>
Tested-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>