Add the ability to set the Request a buffer is associated with. This is needed for buffers that live inside a pipeline handler and is temporarily associated with a request as it's being processed inside the pipeline. While we are at it delete a stray semicolon. Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>