PCI: dwc: Restore ATU memory resource setup to use last entry

Prior to commit 0f71c60f ("PCI: dwc: Remove storing of PCI resources"),
the DWC driver was setting up the last memory resource rather than the
first memory resource. This doesn't matter for most platforms which only
have 1 memory resource, but it broke Tegra194 which has a 2nd
(prefetchable) memory region that requires an ATU entry. The first region
on Tegra194 relies on the default 1:1 pass-thru of outbound transactions
and doesn't need an ATU entry.

Fixes: 0f71c60f ("PCI: dwc: Remove storing of PCI resources")
Link: https://lore.kernel.org/r/20201026154852.221483-1-robh@kernel.org


Reported-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
Cc: Gustavo Pimentel <gustavo.pimentel@synopsys.com>