Altix: SN ACPI hotplug support.

A few minor changes to the way slot/device fixup is done.

No need to be calling sn_pci_controller_fixup(), as
a root bus cannot be hotplugged.

Signed-off-by: John Keller <jpk@sgi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>