phy: qcom: qmp-pcie: register second optional PHY AUX clock

The PCIe Gen4x2 PHY found in the SM8[456]50 SoCs have a second clock,
add the code to register it for PHYs configs that sets a aux_clock_rate.

In order to get the right clock, add qmp_pcie_clk_hw_get() which uses
the newly introduced QMP_PCIE_PIPE_CLK & QMP_PCIE_PHY_AUX_CLK clock
IDs and also supports the legacy bindings by returning the PIPE clock
when #clock-cells=0.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240322-topic-sm8x50-upstream-pcie-1-phy-aux-clk-v2-3-3ec0a966d52f@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>