PCI: dwc: Detect iATU settings after getting "addr_space" resource

Previously, dw_pcie_ep_init() did:

  dw_pcie_iatu_detect(pci);
  res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space");
  if (!res)
    return -EINVAL;

The platform_get_resource_byname() can fail, and dw_pcie_iatu_detect()
doesn't depend on the "addr_space" resource, so delay it until afterwards,
i.e.,

  platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space");
  dw_pcie_iatu_detect(pci);

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20220624143947.8991-3-Sergey.Semin@baikalelectronics.ru


Signed-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>