The PipelineHandlerFactory::create() function has no need to modify the
factory instance. Make it const, as well as the createInstance()
function.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Xavier Roumegue <xavier.roumegue@oss.nxp.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>