message: fix logic for using cusparse
diff: @@ -619,7 +619,7 @@ void SparseMatrix::AddMult(const Vector &x, Vector &y, const double a) const
  //Skip if matrix has no non-zeros
  if (nnz == 0) {return;}
  - if (useCuSparse)
  + if (Device::Allows(Backend::CUDA_MASK) && useCuSparse)
  {
  #ifdef MFEM_USE_CUDA
  const double alpha = a;
  