MFC 261243:
Some BIOSes incorrectly use standard memory resource ranges to list
the memory ranges that they decode for downstream devices rather than
creating ResourceProducer range resource entries.  The result is that
we allocate the full range to the PCI root bridge device causing
allocations in child devices to all fail.

As a workaround, ignore any standard memory resources on a PCI root
bridge device.  It is normal for a PCI root bridge to allocate an I/O
resource for the I/O ports used for PCI config access, but I have not
seen any PCI root bridges that legitimately allocate a memory resource.