drm/ttm: update bulk move object of ghost BO

[Why]
Ghost BO is released with non-empty bulk move object. There is a
warning trace:
WARNING: CPU: 19 PID: 1582 at ttm/ttm_bo.c:366 ttm_bo_release+0x2e1/0x2f0 [amdttm]
Call Trace:
  amddma_resv_reserve_fences+0x10d/0x1f0 [amdkcl]
  amdttm_bo_put+0x28/0x30 [amdttm]
  amdttm_bo_move_accel_cleanup+0x126/0x200 [amdttm]
  amdgpu_bo_move+0x1a8/0x770 [amdgpu]
  ttm_bo_handle_move_mem+0xb0/0x140 [amdttm]
  amdttm_bo_validate+0xbf/0x100 [amdttm]

[How]
The resource of ghost BO should be moved to LRU directly, instead of
using bulk move. The bulk move object of ghost BO should set to NULL
before function ttm_bo_move_to_lru_tail_unlocked.

v2: set bulk move to NULL manually if no resource associated with ghost BO

Fixed: 5b951e487fd6bf5f ("drm/ttm: fix bulk move handling v2")
Signed-off-by: ZhenGuo Yin <zhenguo.yin@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220906084619.2545456-1-zhenguo.yin@amd.com