dnn-layer-mathbinary-test: add unit test for 'mul'

Signed-off-by: Guo, Yejun <yejun.guo@intel.com>

tests/dnn/dnn-layer-mathbinary-test.c

@@ -34,6 +34,8 @@ static float get_expected(float f1, float f2, DNNMathBinaryOperation op)
         return f1 - f2;
     case DMBO_ADD:
         return f1 + f2;
+    case DMBO_MUL:
+        return f1 * f2;
     default:
         av_assert0(!"not supported yet");
         return 0.f;
@@ -190,5 +192,8 @@ int main(int argc, char **argv)
     if (test(DMBO_ADD))
         return 1;
 
+    if (test(DMBO_MUL))
+        return 1;
+
     return 0;
 }