Here is the patch that uses a cpu hotplug callback, to allow dynamic support
of cpu id for classes in sysfs.

This patch applies on top of the one I sent out earlier that Greg included.
I do not have access to hardware that supports cpu hotswapping (virtually or not)
so have not been able to test that aspect of the patch. However, the original
functionality of listing static cpu's still works.

Please consider for testing or inclusion.
Signed-off-by: Hanna Linder <hannal@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>