Move the metadata retrieved when dequeuing a V4L2 buffer into a FrameMetadata object. This is done as a step to migrate to the FrameBuffer interface as the functions added to Buffer around FrameMetadata match the ones in FrameBuffer. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>