PCI: qcom-ep: Setup PHY to work in EP mode

Call phy_set_mode_ext() to notify the PHY driver that the PHY is being
used in the EP mode.

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Jingoo Han <jingoohan1@gmail.com>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20220927092207.161501-6-dmitry.baryshkov@linaro.org