fix truncated_gaussian seed (#28777)

paddle/fluid/operators/truncated_gaussian_random_op.cu

@@ -109,13 +109,13 @@ class GPUTruncatedGaussianRandomKernel : public framework::OpKernel<T> {
           thrust::device_ptr<T>(data),
           TruncatedNormalOffset<T>(mean, std, std::numeric_limits<T>::min(),
                                    seed_offset.first, gen_offset));
-    }
-
+    } else {
       thrust::transform(
           index_sequence_begin, index_sequence_begin + size,
           thrust::device_ptr<T>(data),
           TruncatedNormal<T>(mean, std, std::numeric_limits<T>::min(), seed));
     }
+  }
 };
 
 }  // namespace operators