drm/mgag200: remove unused validate_sequence

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/mgag200/mgag200_drv.h

@@ -195,7 +195,6 @@ struct mga_device {
 		struct drm_global_reference mem_global_ref;
 		struct ttm_bo_global_ref bo_global_ref;
 		struct ttm_bo_device bdev;
-		atomic_t validate_sequence;
 	} ttm;
 
 	u32 reg_1e24; /* SE model number */