MPT / PCI: Use pci_stop_and_remove_bus_device_locked()

Race conditions are theoretically possible between the MPT PCI device
removal and the generic PCI bus rescan and device removal that can be
triggered via sysfs.

To avoid those race conditions make the MPT PCI code use
pci_stop_and_remove_bus_device_locked().

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