message: sneak in a small bugfix
  Fixes
diff: @@ -231,8 +231,8 @@ public:
  gko::size_type get_flops() const override
  {
  - auto host_mtx = Mtx::create(mtx_->get_executor());
  - auto host_mtx2 = Mtx::create(mtx_->get_executor());
  + auto host_mtx = Mtx::create(mtx_->get_executor()->get_master());
  + auto host_mtx2 = Mtx::create(mtx_->get_executor()->get_master());
  host_mtx->copy_from(mtx_);
  host_mtx2->copy_from(mtx2_.get());
  // count the individual products a_ik * b_kj
  