media: rkisp1: isp: Use V4L2 subdev active state

Use the V4L2 subdev active state API to store the active format and crop
rectangle. This simplifies the driver not only by dropping the state
stored in the rkisp1_isp structure, but also by replacing the ops_lock
with the state lock.

The rkisp1_isp.sink_fmt field needs to be kept, as it is accessed from
the stats interrupt handler. To simplify the rkisp1_isp_set_sink_fmt()
implementation, the field is now set when starting the ISP, instead of
when setting the format.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>