arm64: dts: renesas: Add initial device tree for RZ SMARC Carrier-II Board

Add the initial device tree for the RZ SMARC Carrier-II.  At the moment
it contains only the serial interface.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230929053915.1530607-26-claudiu.beznea@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>