Add support for iWave RainboW-G20D-Qseven board based on RZ/G1N. Signed-off-by: Biju Das <biju.das@bp.renesas.com> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>