Those are not errors, they're just warnings, fixing them will not make any difference, but if you really want that, just add Return (Zero) in the last line of each of those methods.
Just fixing compile errors won't be of great help, you need to patch your DSDT if you have any problems (which can be fixed via DSDT), read this topic http://Olarila.com/forum/viewtopic.php?f=19&t=634