Revert "ACPI/PCI: Pay attention to device-specific _PXM node values"

This reverts commit bad7dcd9.

bad7dcd9 ("ACPI/PCI: Pay attention to device-specific _PXM node
values") caused boot failures (no console output at all) for Martin [1]
and Ingo [2] on AMD ThreadRipper systems.

Revert the commit until we figure out how to safely use these
device-specific _PXM values.

[1] https://lore.kernel.org/linux-pci/20180912152140.3676-2-Jonathan.Cameron@huawei.com
[2] https://lore.kernel.org/linux-pci/20181113071712.GA2353@gmail.com
Fixes: bad7dcd9

 ("ACPI/PCI: Pay attention to device-specific _PXM node values")
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>