PCI: dwc: Add support to program ATU for >4GB memory

Add support to program the ATU to enable translations for >4GB sizes of
the prefetchable memory apertures.

Link: https://lore.kernel.org/r/20201118144626.32189-3-vidyas@nvidia.com


Tested-by: Thierry Reding <treding@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Jingoo <jingoohan1@gmail.com>