Removing and then adding a PCI slot to a running partition results in
a kernel panic. The current code attempts to add iospace for an entire
root bus, which is inappropriate, and silently fails.  When a pci device
tries to use the iospace, a page fault is taken, as the iospace had not
been mapped, and of course the page fault cannot be resolved.

This only occurs for PCI adapters using pio, which may be why it hadn't
been seen earlier (this seems to have been broken for a while).
This patch has survived testing of dozens of slot add and removes.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Acked-by: John Rose <johnrose@austin.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>