Add support for the LCD Controller found on i.MX21 and i.MX25.

It targets to be a drop in replacement for the imx-fb driver.

[ukl: Rebase to a newer kernel version, various smaller fixes and
improvements]
Signed-off-by: Marian Cichy <m.cichy@pengutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230306115249.2223042-2-u.kleine-koenig@pengutronix.deSigned-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230306115249.2223042-3-u.kleine-koenig@pengutronix.de