libcamera: camera_sensor: Expose the camera device

Expose the device backing the CameraSensor instance.

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

include/libcamera/internal/camera_sensor.h

@@ -61,6 +61,8 @@ public:
 	ControlList getControls(const std::vector<uint32_t> &ids);
 	int setControls(ControlList *ctrls);
 
+	V4L2Subdevice *device() { return subdev_.get(); }
+
 	const ControlList &properties() const { return properties_; }
 	int sensorInfo(CameraSensorInfo *info) const;