fix import

Author: Valentine233

torchao/prototype/inductor/qsdpa_lowering.py

@@ -3,7 +3,7 @@
 import sympy
 import torch
 from torch._inductor.ir import ChoiceCaller, FixedLayout, TensorBox, get_fill_order
-from torch._inductor.kernel.flex_attention import construct_strides, maybe_realize
+from torch._inductor.kernel.flex.common import construct_strides, maybe_realize
 from torch._inductor.lowering import register_lowering
 from torch._inductor.select_algorithm import (
     ExternKernelChoice,