Build failures in v4.9.y.queue, v4.4.y.queue

arm:allmodconfig, arm:multi_v7_defconfig:

drivers/gpu/drm/rockchip/rockchip_drm_drv.c: In function 'rockchip_drm_platform_shutdown': drivers/gpu/drm/rockchip/rockchip_drm_drv.c:486:3: error: implicit declaration of function 'drm_atomic_helper_shutdown'

Seen in both v4.4.y.queue and v4.9.y.queue.

Guenter