Fix simple bug in eFexEMRoI_v1.cxx

The Rhad and Wstot results getters were reading the wrong bits from the RoI words (swapped with each other). This corrects that (swaps them back).

This doesn't affect the persistent data formats, doesn't require schema evolution, it's purely a matter of interpreting the RoI word correctly. The only effect is that people calling the functions to access the Rhad and Wstot trigger bits will get the correct results now.