PCI: iproc: Remove redundant outbound properties

Remove the following outbound related device tree properties:

  brcm,pcie-ob-window-size
  brcm,pcie-ob-oarr-size

The above two properties are a bit duplicated in functions.  In addition,
the next generation iProc PCIe controller has outbound mapping window that
supports more than just two sizes, which cannot be properly supported by
these properties.

[bhelgaas: changelog]
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Scott Branden <scott.branden@broadcom.com>