ACPI / dock: Do not leak memory on falilures to add a dock station

The function creating and registering dock station objects,
dock_add(), leaks memory if there's an error after it's walked
the ACPI namespace calling find_dock_devices(), because it doesn't
free the list of dependent devices it's just created in those cases.

Fix that issue by adding the missing code to free the list of
dependent devices on errors.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/dock.c

@@ -115,6 +115,16 @@ add_dock_dependent_device(struct dock_station *ds, acpi_handle handle)
 	return 0;
 }
 
+static void remove_dock_dependent_devices(struct dock_station *ds)
+{
+	struct dock_dependent_device *dd, *aux;
+
+	list_for_each_entry_safe(dd, aux, &ds->dependent_devices, list) {
+		list_del(&dd->list);
+		kfree(dd);
+	}
+}
+
 /**
  * dock_init_hotplug - Initialize a hotplug device on a docking station.
  * @dd: Dock-dependent device.
@@ -895,6 +905,7 @@ static int __init dock_add(acpi_handle handle)
 	return 0;
 
 err_rmgroup:
+	remove_dock_dependent_devices(dock_station);
 	sysfs_remove_group(&dd->dev.kobj, &dock_attribute_group);
 err_unregister:
 	platform_device_unregister(dd);