dt-bindings: bus: Document Broadcom GISB arbiter 74165 compatible

The 74165 chip introduces a new layout for the GISB arbiter which is not
identical to previous chips, document the new compatible that we are
going to key off.

Link: https://lore.kernel.org/r/20240111231539.783785-2-florian.fainelli@broadcom.com


Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>