RFR (T) 8225760: oop::raw_set_obj isn't needed

[Roman Kennke]

This is probably a left-over from an earlier Shenandoah. Patch looks
good to me.

Thanks,
Roman


> Remove the public function and add to set_obj.  Ran tier1 tests locally.
> 
> open webrev at http://cr.openjdk.java.net/~coleenp/2020/8225760.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8225760
> 
> Thanks,
> Coleen
>