media: rzg2l-cru: Add vidioc_enum_framesizes()

Add a callback to implement the VIDIOC_ENUM_FRAMESIZES ioctl for the
CRU driver.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Daniel Scally <dan.scally+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/20250625-rzg2l-cru-v6-2-a9099ed26c14@ideasonboard.com


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