dt-bindings: phy: qcom,sc8280xp-qmp-pcie-phy: drop second output clock name

There is no need to specify exact name for the second (AUX) output
clock. It has never been used for the lookups based on the system clock
name. Partially revert commit 72bea132 ("dt-bindings: phy:
qcom,sc8280xp-qmp-pcie-phy: document PHY AUX clock on SM8[456]50 SoCs"),
returning compatibility with the existing device tree: reduce
clock-output-names to always contain a single entry.

Fixes: 72bea132

 ("dt-bindings: phy: qcom,sc8280xp-qmp-pcie-phy: document PHY AUX clock on SM8[456]50 SoCs")
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240614-fix-pcie-phy-compat-v3-2-730d1811acf4@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>