Multiple race conditions are possible between the addition and removal of
PCI devices during ACPI PCI host bridge hotplug and the generic PCI bus
rescan and device removal that can be triggered via sysfs.

To avoid those race conditions make the ACPI PCI host bridge addition and
removal code use global PCI rescan-remove locking.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>