phy: qcom-qmp-pcie: add support for sc8280xp 4-lane PHYs

The PCIe2 and PCIe3 controllers and PHYs on SC8280XP can be used in
4-lane mode or as separate controllers and PHYs in 2-lane mode (e.g. as
PCIe2A and PCIe2B).

Add support for fetching the 4-lane configuration from the TCSR and
programming the lane registers of the second port when in 4-lane mode.

Signed-off-by: Johan Hovold <johan+linaro@kernel.org>