phy: qcom-qmp-pcie: drop multi-PHY support

Each PCIe QMP PHY device provides just a single PCIe PHY. Drop support
for handling multiple child PHYs.

Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Bjorn Andersson <bjorn.andersson@linaro.org> # UFS, PCIe and USB on SC8180X
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220607213203.2819885-25-dmitry.baryshkov@linaro.org


Signed-off-by: Vinod Koul <vkoul@kernel.org>