Revert "drm/rockchip: Allow driver to be shutdown on reboot/kexec"

This reverts commit 7f3ef5dedb.

It causes new warnings [1] on shutdown when running the Google Kevin or
Scarlet (RK3399) boards under Chrome OS. Presumably our usage of DRM is
different than what Marc and Heiko test.

We're looking at a different approach (e.g., [2]) to replace this, but
IMO the revert should be taken first, as it already propagated to
-stable.

[1] Report here:
http://lkml.kernel.org/lkml/20181205030127.GA200921@google.com

WARNING: CPU: 4 PID: 2035 at drivers/gpu/drm/drm_mode_config.c:477 drm_mode_config_cleanup+0x1c4/0x294
...
 Call trace:
  drm_mode_config_cleanup+0x1c4/0x294
  rockchip_drm_unbind+0x4c/0x8c
  component_master_del+0x88/0xb8
  rockchip_drm_platform_remove+0x2c/0x44
  rockchip_drm_platform_shutdown+0x20/0x2c
  platform_drv_shutdown+0x2c/0x38
  device_shutdown+0x164/0x1b8
  kernel_restart_prepare+0x40/0x48
  kernel_restart+0x20/0x68
...
 Memory manager not clean during takedown.
 WARNING: CPU: 4 PID: 2035 at drivers/gpu/drm/drm_mm.c:950 drm_mm_takedown+0x34/0x44
...
  drm_mm_takedown+0x34/0x44
  rockchip_drm_unbind+0x64/0x8c
  component_master_del+0x88/0xb8
  rockchip_drm_platform_remove+0x2c/0x44
  rockchip_drm_platform_shutdown+0x20/0x2c
  platform_drv_shutdown+0x2c/0x38
  device_shutdown+0x164/0x1b8
  kernel_restart_prepare+0x40/0x48
  kernel_restart+0x20/0x68
...

[2] https://patchwork.kernel.org/patch/10556151/
    https://www.spinics.net/lists/linux-rockchip/msg21342.html
    [PATCH] drm/rockchip: shutdown drm subsystem on shutdown

Fixes: 7f3ef5dedb ("drm/rockchip: Allow driver to be shutdown on reboot/kexec")
Cc: Jeffy Chen <jeffy.chen@rock-chips.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Vicente Bergas <vicencb@gmail.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: stable@vger.kernel.org
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20181205181657.177703-1-briannorris@chromium.org

drivers/gpu/drm/rockchip/rockchip_drm_drv.c

@@ -448,11 +448,6 @@ static int rockchip_drm_platform_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static void rockchip_drm_platform_shutdown(struct platform_device *pdev)
-{
-	rockchip_drm_platform_remove(pdev);
-}
-
 static const struct of_device_id rockchip_drm_dt_ids[] = {
 	{ .compatible = "rockchip,display-subsystem", },
 	{ /* sentinel */ },
@@ -462,7 +457,6 @@ MODULE_DEVICE_TABLE(of, rockchip_drm_dt_ids);
 static struct platform_driver rockchip_drm_platform_driver = {
 	.probe = rockchip_drm_platform_probe,
 	.remove = rockchip_drm_platform_remove,
-	.shutdown = rockchip_drm_platform_shutdown,
 	.driver = {
 		.name = "rockchip-drm",
 		.of_match_table = rockchip_drm_dt_ids,