Fix a test failure in mlas (microsoft#24930)

The original code has a divided-by-zero error.

Author: snnn

onnxruntime/test/mlas/unittest/test_scaleoutput.cpp

@@ -22,7 +22,7 @@ class MlasScaleOutputTest : public MlasTestBase {
                                                             std::numeric_limits<int16_t>::max());
 
     for (size_t s = 0; s < M * N; s++) {
-      Input[s] = int_distribution(generator);
+      Input[s] = int_distribution(generator);  // It could be zero
       Output[s] = OutputRef[s] = real_distribution(generator);
     }
 
@@ -52,10 +52,14 @@ class MlasScaleOutputTest : public MlasTestBase {
     constexpr float epsilon = 1e-6f;
 
     for (size_t n = 0; n < M * N; n++) {
-      float diff = std::fabs((Output[n] - OutputRef[n]) / OutputRef[n]);
+      float outvalue = OutputRef[n];  // When `AccumulateMode` is false, there is a high chance that this value could be zero
+      float diff = std::fabs(Output[n] - outvalue);
+      if (outvalue != 0) {
+        diff /= outvalue;
+      }
       ASSERT_LE(diff, epsilon)
           << " @[" << n / N << "," << n % N << "], total:[" << M << "," << N << "], got:"
-          << Output[n] << ", expecting:" << OutputRef[n];
+          << Output[n] << ", expecting:" << outvalue;
     }
   }