dt-bindings: clock: qcom,aoncc-sm8250: add missing audio clock

The SM8250 DTS uses three clocks as input to LPASS AON Clock Controller
(althopugh Linux driver seems not needing it), so document the missing
audio voting clock.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221104174656.123979-2-krzysztof.kozlowski@linaro.org