support broadcast of Mul cpu op

mindspore/ccsrc/backend/kernel_compiler/cpu/arithmetic_cpu_kernel.cc

@@ -32,7 +32,9 @@ void ArithmeticCPUKernel::AssignAdd(T *input1, const T *input2, T *out, size_t s
 template <typename T>
 void ArithmeticCPUKernel::Add(const T *input1, const T *input2, T *out, size_t start, size_t end) {
   for (size_t i = start; i < end; i++) {
-    out[i] = input1[i] + input2[i];
+    std::vector<size_t> idx;
+    GenIndex(i, &idx);
+    out[i] = input1[idx[0]] + input2[idx[1]];
   }
 }
 
@@ -48,7 +50,9 @@ void ArithmeticCPUKernel::Sub(const T *input1, const T *input2, T *out, size_t s
 template <typename T>
 void ArithmeticCPUKernel::Mul(const T *input1, const T *input2, T *out, size_t start, size_t end) {
   for (size_t i = start; i < end; i++) {
-    out[i] = input1[i] * input2[i];
+    std::vector<size_t> idx;
+    GenIndex(i, &idx);
+    out[i] = input1[idx[0]] * input2[idx[1]];
   }
 }