PCI: imx6: Fetch dbi2 and iATU base addesses from DT

PCI: imx6: Fetch dbi2 and iATU base addesses from DT

Since dw_pcie_get_resources() gets the dbi2 and iATU base addresses from
DT, remove the code from the imx6 driver that does the same.

Upstream DTSes have not enabled Endpoint function. So nothing is broken for
old upstream DTBs.

Link: https://lore.kernel.org/r/20241126075702.4099164-4-hongxing.zhu@nxp.com
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>