dt-bindings: mailbox: qcom,apcs-kpss-global: drop mbox-names from example

Qualcomm G-Link RPM edge bindings do not allow and do not use mbox-names
property.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230208101545.45711-4-krzysztof.kozlowski@linaro.org