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

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 <u.kleine-koenig@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230706092731.2630232-1-u.kleine-koenig@pengutronix.de