dt-bindings: arm64: bcmbca: Add Zyxel EX3510-B based on BCM4906

dt-bindings: arm64: bcmbca: Add Zyxel EX3510-B based on BCM4906

This is a series (EX3510-B0 and EX3510-B1) of residential gateways based
on BCM4906, a stripped-down version of the BCM4908 SoC. Although Zyxel's
marketing materials call this a "series," the EX3510-B1 appears to be a
very minor revision of the EX3510-B0, with only changes that are
transparent to software. As far as Linux is concerned, this "series"
effectively represents a single model.

Signed-off-by: Sam Edwards <CFSworks@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20241009215454.1449508-2-CFSworks@gmail.com
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>