dt-bindings: net: dsa: add bindings for Renesas RZ/N1 Advanced 5 port switch

Add bindings for Renesas RZ/N1 Advanced 5 port switch. This switch is
present on Renesas RZ/N1 SoC and was probably provided by MoreThanIP.
This company does not exists anymore and has been bought by Synopsys.
Since this IP can't be find anymore in the Synospsy portfolio, lets use
Renesas as the vendor compatible for this IP.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>