Add Lod information for gather_nd & scatter_nd (#21404)

* add lod information, test=develop

* add lod, test=develop

* fix lod, test=develop

* fix lod, test=develop

paddle/fluid/operators/gather_nd_op.cc

@@ -55,6 +55,7 @@ class GatherNdOp : public framework::OperatorWithKernel {
     }
 
     ctx->SetOutputDim("Out", framework::make_ddim(result_dims));
+    ctx->ShareLoD("X", /*->*/ "Out");
   }
 
  protected:

paddle/fluid/operators/scatter_nd_add_op.cc

@@ -64,6 +64,7 @@ class ScatterNdAddOp : public framework::OperatorWithKernel {
                         "Updates has wrong shape");
     }
     ctx->SetOutputDim("Out", ref_dims);
+    ctx->ShareLoD("X", /*->*/ "Out");
   }
 
  protected: