media: cedrus: Properly signal size in mode register

Mode register also holds information if video width is bigger than 2048
and if it is equal to 4096.

Rework cedrus_engine_enable() to properly signal this properties.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Acked-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>