media: uapi: videodev2: Add V4L2_META_FMT_RK_ISP1_EXT_PARAMS

media: uapi: videodev2: Add V4L2_META_FMT_RK_ISP1_EXT_PARAMS

The rkisp1 driver stores ISP configuration parameters in the fixed
rkisp1_params_cfg structure. As the members of the structure are part of
the userspace API, the structure layout is immutable and cannot be
extended further. Introducing new parameters or modifying the existing
ones would change the buffer layout and cause breakages in existing
applications.

The allow for future extensions to the ISP parameters, introduce a new
extensible parameters format, with a new format 4CC. Document usage of
the new format in the rkisp1 admin guide.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>