Arrays of arrays, even arrays of strings, are not supported by
the current `ControlValue` mechanism, so disable them for now
to trigger compile time errors if attempts are made to use them.
Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>