drm/ttm: kill off some members to ttm_validate_buffer

This reorders the list to keep track of what buffers are reserved,
so previous members are always unreserved.

This gets rid of some bookkeeping that's no longer needed,
while simplifying the code some.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>

drivers/gpu/drm/qxl/qxl_release.c

@@ -349,7 +349,6 @@ void qxl_release_fence_buffer_objects(struct qxl_release *release)
 
 		ttm_bo_add_to_lru(bo);
 		__ttm_bo_unreserve(bo);
-		entry->reserved = false;
 	}
 	spin_unlock(&glob->lru_lock);
 	ww_acquire_fini(&release->ticket);