PCI: dwc: Do not remap invalid res

On imx6 and perhaps others when pcie probes you get a:
imx6q-pcie 33800000.pcie: invalid resource

This occurs because the atu is not specified in the DT and as such it
should not be remapped.

Link: https://lore.kernel.org/r/20211101180243.23761-1-tharvey@gateworks.com


Fixes: 281f1f99 ("PCI: dwc: Detect number of iATU windows")
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Richard Zhu <hongxing.zhu@nxp.com>
Cc: Richard Zhu <hongxing.zhu@nxp.com>