media: rcar-vin: Store platform info with group structure

When the transition of Gen2 to use groups are complete the platform
specific information can be retrieved from the group instead of being
duplicated in each VIN's private data structure.

Prepare for this by already adding the information to the group
structure so it can be used without first having to find the group from
a VIN instances private data.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/20250613153434.2001800-3-niklas.soderlund+renesas@ragnatech.se


Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>