Since DWC PCIe v4.70a, the controller version and version type can be read
from the PORT_LOGIC.PCIE_VERSION_OFF and PORT_LOGIC.PCIE_VERSION_TYPE_OFF
registers respectively.

Read the version from those registers and warn if if's different from the
version we got from the device tree.

We can only read the version after platform-specific drivers have done any
DBI-related initialization, such as reference clock activation.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20220624143947.8991-5-Sergey.Semin@baikalelectronics.ruSigned-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>