[fix] Use return pointers from fromConstInitializer in EqualExp-visitor

After refactoring in 0215b469 member variables e1/e2 from input argument e were used. So to keep the old behaviour, e1 and e2 from fromConstInitializer should be used instead.

I was not able to create a test to trigger any differences between e->e1/e2 and e1/e2 in an EqualExp but I assume it should be possible.