dt-bindings: net: snps,dwmac: add "renesas,rzn1" compatible

Add "renesas,rzn1-gmac" and "renesas,r9a06g032-gmac" compatible strings.

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