media: ipu3-cio2: Use V4L2 subdev active state

Replace storage of the active format in the cio2_queue structure with
usage of V4L2 subdev active state. This simplifies locking in the
driver, and drops usage of the deprecated subdev .open() internal
operation.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
[Sakari Ailus: keep fmt_default non-static to keep clang happy.]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>