[PATCH] acpi bridge hotadd: Prevent duplicate bus numbers when scanning PCI bridge

When hot-plugging a root bridge, as we try to assign bus numbers we may find
that the hotplugged hieratchy has more PCI to PCI bridges (i.e.  bus
requirements) than available.  Make sure we don't step over an existing bus
when that happens.

Signed-off-by: Rajesh Shah <rajesh.shah@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>