drm/ttm: Do not add non-system domain BO into swap list

BO would be added into swap list if it is validated into system domain.
If BO is validated again into non-system domain, say, VRAM domain. It
actually should not be in the swap list.

Signed-off-by: xinhui pan <[e-mail]>
Acked-by: Guchun Chen <[e-mail]>
Acked-by: Alex Deucher <[e-mail]>
Reviewed-by: Christian König <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Christian König <[e-mail]>

drivers/gpu/drm/ttm/ttm_bo.c

···
 
 		swap = &ttm_glob.swap_lru[bo->priority];
 		list_move_tail(&bo->swap, swap);
+	} else {
+		list_del_init(&bo->swap);
 	}
 
 	if (bdev->funcs->del_from_lru_notify)