media: vimc: stream: add docs to struct vimc_stream

#define VIMC_STREAMER_PIPELINE_MAX_SIZE 16

/**

 * struct vimc_stream - struct that represents a stream in the pipeline

 *

 * @pipe:		the media pipeline object associated with this stream

 * @ved_pipeline:	array containing all the entities participating in the

 * stream. The order is from a video device (usually a capture device) where

 * stream_on was called, to the entity generating the first base image to be

 * processed in the pipeline.

 * @pipe_size:		size of @ved_pipeline

 * @kthread:		thread that generates the frames of the stream.

 *

 * When the user call stream_on in a video device, struct vimc_stream is

 * used to keep track of all entities and subdevices that generates and

 * process frames for the stream.

 */

struct vimc_stream {

	struct media_pipeline pipe;

	struct vimc_ent_device *ved_pipeline[VIMC_STREAMER_PIPELINE_MAX_SIZE];