PCI: Make PCI device numa-node attribute visible in sysfs

Export the numa-node attribute of PCI devices in sysfs so that
user applications may choose where to be placed accordingly.

Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>