fix truncated_gaussian seed (#28777)

paddle/fluid/operators/truncated_gaussian_random_op.cu

@@ -109,12 +109,12 @@ 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));
     }
-
-    thrust::transform(
-        index_sequence_begin, index_sequence_begin + size,
-        thrust::device_ptr<T>(data),
-        TruncatedNormal<T>(mean, std, std::numeric_limits<T>::min(), seed));
   }
 };