platform / x86: Use global PCI rescan-remove locking

Multiple race conditions are possible between the rfkill hotplug in the
asus-wmi and eeepc-laptop drivers and the generic PCI bus rescan and device
removal that can be triggered via sysfs.

To avoid those race conditions make asus-wmi and eeepc-laptop use global
PCI rescan-remove locking around the rfkill hotplug.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>