dt-bindings: clock: qcom,a53pll: Allow opp-table subnode

Allow placing an opp-table as a subnode that can be assigned using
operating-points-v2 to specify the frequency table for the PLL.

Signed-off-by: Luca Weiss <luca@lucaweiss.eu>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240619-msm8226-cpufreq-v1-2-85143f5291d1@lucaweiss.eu


Signed-off-by: Bjorn Andersson <andersson@kernel.org>