Removing unused NMSSM two-loop Higgs function calls

Dear Ben,

Peter found that the output of some NMSSM two-loop Higgs function calls in `nmssmsoftsusy.cpp` are unused (they were used for testing in the past).  These commits remove these function calls and do a little clean-up.

If you agree with these changes, please feel free to merge them into your master branch.

Best,
Alex