powerpc/pci: Reorder pci bus/bridge unregistration during PHB removal

commit 73400565 upstream.

Commit bcdde7e2 made __sysfs_remove_dir() recursive and introduced a BUG_ON
during PHB removal while attempting to delete the power managment attribute
group of the bus. This is a result of tearing the bridge and bus devices down
out of order in remove_phb_dynamic. Since, the the bus resides below the bridge
in the sysfs device tree it should be torn down first.

This patch simply moves the device_unregister call for the PHB bridge device
after the device_unregister call for the PHB bus.

Fixes: bcdde7e2 ("sysfs: make __sysfs_remove_dir() recursive")
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/powerpc/platforms/pseries/pci_dlpar.c

@@ -118,10 +118,10 @@ int remove_phb_dynamic(struct pci_controller *phb)
 		}
 	}
 
-	/* Unregister the bridge device from sysfs and remove the PCI bus */
-	device_unregister(b->bridge);
+	/* Remove the PCI bus and unregister the bridge device from sysfs */
 	phb->bus = NULL;
 	pci_remove_bus(b);
+	device_unregister(b->bridge);
 
 	/* Now release the IO resource */
 	if (res->flags & IORESOURCE_IO)