message: fix blas benchmark gemm
diff: @@ -271,7 +271,7 @@ public:
  sizeof(etype);
  }
  - void run() override { B_->apply(lend(A_), lend(C_)); }
  + void run() override { A_->apply(lend(B_), lend(C_)); }
  private:
  std::unique_ptr<gko::matrix::Dense<etype>> A_;
  @@ -317,7 +317,7 @@ public:
  void run() override
  {
  - B_->apply(lend(alpha_), lend(A_), lend(beta_), lend(C_));
  + A_->apply(lend(alpha_), lend(B_), lend(beta_), lend(C_));
  }
  private:
  