The following patch implements the registration of PCI Host Bridges as hotplug
slots.  Only host bridges that are dynamically removable will be registered.
The hotplug slots directory goes from looking like this:

# ls /sys/bus/pci/slots
.             0000:00:02.2  0001:00:02.4  0002:00:02.2  30000000
..            0000:00:02.4  0001:00:02.6  0002:00:02.4  control
0000:00:02.0  0001:00:02.2  0002:00:02.0  0002:00:02.6

to this:

# ls /sys/bus/pci/slots
.             0000:00:02.0  0001:00:00.0  0001:00:02.6  0002:00:02.2  30000000
..            0000:00:02.2  0001:00:02.2  0002:00:00.0  0002:00:02.4  control
0000:00:00.0  0000:00:02.4  0001:00:02.4  0002:00:02.0  0002:00:02.6

This work is precursory to the DLPAR module changes that implement
addition/removal of these bridges.  Please apply if there are no objections.
Signed-off-by: John Rose <johnrose@austin.ibm.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>