hotplug/rpaphp: Remove unused error path code

Commit f46753c5 ("PCI: introduce pci_slot") removed the need for this error path.  Eliminate this warning:

drivers/pci/hotplug/rpaphp_slot.c: In function 'rpaphp_register_slot':
drivers/pci/hotplug/rpaphp_slot.c:151: warning: label 'sysfs_fail' defined but not used

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>