removing the comments from the NonlinearSolver_impl

which is from the development process.

opm/autodiff/NonlinearSolver_impl.hpp

@@ -127,9 +127,6 @@ namespace Opm
         failureReport_ = SimulatorReport();
 
         // Do model-specific once-per-step calculations.
-        // TODO: this is not the correct fix, possibly breaking the sequential solver
-        // TODO: the only reason to do this is that the wellPotentials() is part of the well_state, which will be modified
-        // during the well_potential calculation
         model_->prepareStep(timer, initial_reservoir_state, initial_well_state);
 
         int iteration = 0;