!7219 Adapt matmul's input tensor shape for onnx model

Merge pull request !7219 from zhanyuan/tmp

mindspore/lite/src/ops/matmul.cc

@@ -105,6 +105,12 @@ int MatMul::InferShape(std::vector<Tensor *> inputs_, std::vector<Tensor *> outp
 
   std::vector<int> a_shape = input0->shape();
   std::vector<int> b_shape = input1->shape();
+
+  if (a_shape.size() == 4 && a_shape[2] == 1 && a_shape[3] == 1) {
+    a_shape.resize(2);
+    input0->set_shape(a_shape);
+  }
+
   if (a_shape.size() < 2 || b_shape.size() < 2) {
     MS_LOG(ERROR) << "inputs shape is invalid";
     return RET_INPUT_TENSOR_ERROR;