The `setVoltage()` function should be called even when `ENABLE_VSELECT` is disabled because `ENABLE_3V3FIX` also uses it. There is no resource cost to do this as when both options are disabled the compiler will optimize this function out. This just "future proofs" the code so if that function ever does more it doesn't need updated everywhere. This applies to `setup_FlashVoltage()` as well.
The changes to OSCR.cpp are just for code formatting and additional comments to clarify this.