[ROCm] Fix for import when building with upstream triton for gfx1100 for gpt-oss serving (#29127)

Signed-off-by: Hongxia Yang <hongxia.yang@amd.com>

vllm/model_executor/layers/quantization/utils/mxfp4_utils.py

@@ -39,15 +39,15 @@ def _swizzle_mxfp4(quant_tensor, scale, num_warps):
         value_layout = StridedLayout
         scale_layout = StridedLayout
     elif current_platform.is_rocm():
-        from triton_kernels.tensor_details.layout import (
-            GFX950MXScaleLayout,
-            StridedLayout,
-        )
-
         from vllm.platforms.rocm import on_gfx950
 
         value_layout = StridedLayout
-        scale_layout = GFX950MXScaleLayout if on_gfx950() else StridedLayout
+        if on_gfx950():
+            from triton_kernels.tensor_details.layout import GFX950MXScaleLayout
+
+            scale_layout = GFX950MXScaleLayout
+        else:
+            scale_layout = StridedLayout
     else:
         value_layout, value_layout_opts = layout.make_default_matmul_mxfp4_w_layout(
             mx_axis=1