media: cedrus: Remove cedrus_codec enum

Last user of cedrus_codec enum is cedrus_engine_enable() but this
argument is completely redundant. Same information can be obtained via
source pixel format. Let's remove this argument and enum.

No functional changes intended.

Acked-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>