PCI: fix rpadlpar pci hotplug driver sysfs usage

When Greg "fixed" the sysfs usage of that driver a while back, he seem
to have introduced a bug where the quotes are added around the name of
our specific sysfs files, thus breaking the user space tool.

This fixes it. Tested DLPAR operations on a POWER6 machine successfully.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>