media: rzg2l-cru: Add image_conv offset to OF data

Add `image_conv` field to the `rzg2l_cru_info` structure to store the
register offset for image conversion control. RZ/G2L uses `ICnMC`, while
RZ/G3E and RZ/V2H(P) use `ICnIPMC_C0`.

Update `rzg2l_cru_initialize_image_conv()` and `rzg2l_cru_csi2_setup()`
to use this `image_conv` offset from the OF data, facilitating future
support for RZ/G3E and RZ/V2H(P) SoCs.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
Link: https://lore.kernel.org/r/20250411170624.472257-14-tommaso.merciai.xr@bp.renesas.com


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