Add driver for Renesas Capture Engine Unit (CEU).

The CEU interface supports capturing 'data' (YUV422) and 'images'
(NV[12|21|16|61]).

This driver aims to replace the soc_camera-based sh_mobile_ceu one.

Tested with ov7670 camera sensor, providing YUYV_2X8 data on Renesas RZ
platform GR-Peach.

Tested with ov7725 camera sensor on SH4 platform Migo-R.
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com: added two 'fall-through' comments]
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>