arm: a37xx: pci: Increase PCIe IO size from 64 KiB to 1 MiB

Commit 079b35a2 ("arm: a37xx: pci: Increase PCIe MEM size from 16 MiB
to 127 MiB") increased size of PCIe MEM to 127 MiB, which is the maximal
possible size for allocated 128 MiB PCIe window. PCIe IO size in that
commit was unchanged.

Armada 3720 PCIe controller supports 32-bit IO space mapping so it is
possible to assign more than 64 KiB if address space for IO.

Currently controller has assigned 127 MiB + 64 KiB memory and therefore
there is 960 KiB of unused memory. So assign it to IO space by increasing
IO window from 64 KiB to 1 MiB.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 079b35a2 ("arm: a37xx: pci: Increase PCIe MEM size from 16 MiB to 127 MiB")
Reviewed-by: Stefan Roese <sr@denx.de>