!7277 [MSLITE] improve bn fusion

Merge pull request !7277 from ghzl/imrove-bn-fusion

mindspore/lite/src/ops/conv2d.cc

@@ -182,6 +182,16 @@ void Conv2D::PopulaterConv2DMultiGroup(const Primitive &prim, schema::PrimitiveT
   if (input_node->isa<Parameter>()) {
     auto param_node = input_node->cast<ParameterPtr>();
     ConvertConvWeight<float>(param_node);
+    auto abstractBase = param_node->abstract();
+    MS_ASSERT(abstractBase != nullptr);
+    if (utils::isa<abstract::AbstractTensorPtr>(abstractBase)) {
+      auto abstractTensor = utils::cast<abstract::AbstractTensorPtr>(abstractBase);
+      MS_ASSERT(abstractTensor != nullptr);
+      if (utils::isa<abstract::ShapePtr>(abstractTensor->BuildShape())) {
+        auto dims = utils::cast<abstract::ShapePtr>(abstractTensor->BuildShape())->shape();
+        attr->channelIn = dims[kAnfPopulaterOne];
+      }
+    }
   }
 
   primitive->value.type = schema::PrimitiveType_DepthwiseConv2D;