drm/imx/lcdc: Fix double-free of driver data

The struct imx_lcdc driver data is allocated using devm_drm_dev_alloc()
so it must not be explicitly kfree()d.

Also drm_kms_helper_poll_fini() should not be called as there is no
matching drm_kms_helper_poll_init(). So drop the release function
completely.

Fixes: c87e859cdeb5 ("drm/imx/lcdc: Implement DRM driver for imx25")
Signed-off-by: Uwe Kleine-König <[e-mail]>
Reviewed-by: Philipp Zabel <[e-mail]>
Signed-off-by: Philipp Zabel <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/imx/lcdc/imx-lcdc.c

···
 	.atomic_commit_tail = drm_atomic_helper_commit_tail_rpm,
 };
 
-static void imx_lcdc_release(struct drm_device *drm)
-{
-	struct imx_lcdc *lcdc = imx_lcdc_from_drmdev(drm);
-
-	drm_kms_helper_poll_fini(drm);
-	kfree(lcdc);
-}
-
 DEFINE_DRM_GEM_DMA_FOPS(imx_lcdc_drm_fops);
 
 static struct drm_driver imx_lcdc_drm_driver = {
 	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
 	.fops = &imx_lcdc_drm_fops,
 	DRM_GEM_DMA_DRIVER_OPS_VMAP,
-	.release = imx_lcdc_release,
 	.name = "imx-lcdc",
 	.desc = "i.MX LCDC driver",
 	.date = "20200716",