Top-level `const` qualifiers are not useful, so avoid them. This is done either by simply removing the top-level `const`, or making the function return a reference to const where that is appropriate. Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>