drm/msm: remove shutdown callback from msm_platform_driver

The msm_drv_shutdown only makes sense for the KMS-enabled devices, while
msm_platform_driver is only used in the headless case. Remove the
shutdown callback from the driver structure.
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/561644/Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_drv.c

@@ -1297,7 +1297,6 @@ void msm_drv_shutdown(struct platform_device *pdev)
 static struct platform_driver msm_platform_driver = {
 	.probe      = msm_pdev_probe,
 	.remove     = msm_pdev_remove,
-	.shutdown   = msm_drv_shutdown,
 	.driver     = {
 		.name   = "msm",
 	},