PCI hotplug: fix error path in pci_slot's register_slot

Juha Leppnen noticed that an error path in register_slot() wasn't
returning appropriately, leading to a condition where we might access a
kfree'ed pointer, so let's fix that.

Additionally, fix up the copyright information in the file while
we're in there.

Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>