examples: Fix double device closing in manage-prints

The manage-prints command would close the device twice when the user
hits an invalid number or 'n' and no prints need to be deleted.

Simply remove the erroneous call to fix the issue.

examples/manage-prints.c

@@ -197,9 +197,6 @@ on_list_completed (FpDevice     *dev,
                 list_data->ret_value = EXIT_SUCCESS;
               else
                 g_warning ("Invalid finger selected");
-
-              fp_device_close (dev, NULL, (GAsyncReadyCallback) on_device_closed,
-                               list_data);
             }
         }