Add the initial device tree for the RZ/A1 based development board (RSK).
Signed-off-by: NChris Brandt <chris.brandt@renesas.com>
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>