drm/ttm: revert "implement LRU add callbacks v2"

The additional housekeeping had too much CPU overhead,
let's use the BO priorities instead.

agd: also revert hibmc changes

Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-and-Tested-by: Roger.He <Hongbo.He@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/qxl/qxl_ttm.c

@@ -394,8 +394,6 @@ static struct ttm_bo_driver qxl_bo_driver = {
 	.io_mem_reserve = &qxl_ttm_io_mem_reserve,
 	.io_mem_free = &qxl_ttm_io_mem_free,
 	.move_notify = &qxl_bo_move_notify,
-	.lru_tail = &ttm_bo_default_lru_tail,
-	.swap_lru_tail = &ttm_bo_default_swap_lru_tail,
 };
 
 int qxl_ttm_init(struct qxl_device *qdev)