libcamera: media_device: expose media graph model name

Pipeline handlers such as the upcoming ucvideo handler need the model
name to properly name the Camera objects they create. Store the model
name when querying the media device info and handle it in a similar
fashion as the driver name which is already retrieved.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/include/media_device.h

@@ -36,6 +36,7 @@ public:
 
 	const std::string driver() const { return driver_; }
 	const std::string deviceNode() const { return deviceNode_; }
+	const std::string model() const { return model_; }
 
 	const std::vector<MediaEntity *> &entities() const { return entities_; }
 	MediaEntity *getEntityByName(const std::string &name) const;
@@ -50,6 +51,7 @@ public:
 private:
 	std::string driver_;
 	std::string deviceNode_;
+	std::string model_;
 	int fd_;
 	bool valid_;
 	bool acquired_;