ACPI / PCI / hotplug: unlock in error path in acpiphp_enable_slot()

In acpiphp_enable_slot(), there is a missing unlock path
when error occurred.  It needs to be unlocked before returning
an error.
Signed-off-by: Insu Yun <wuninsu@gmail.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/hotplug/acpiphp_glue.c

@@ -953,8 +953,10 @@ int acpiphp_enable_slot(struct acpiphp_slot *slot)
 {
 	pci_lock_rescan_remove();
 
-	if (slot->flags & SLOT_IS_GOING_AWAY)
+	if (slot->flags & SLOT_IS_GOING_AWAY) {
+		pci_unlock_rescan_remove();
 		return -ENODEV;
+	}
 
 	/* configure all functions */
 	if (!(slot->flags & SLOT_ENABLED))