Avoid torch compile graphbreak for older pytorch versions (Comfy-Org#9344)

Turns out torch.compile has some gaps in context manager decorator
syntax support. I've sent patches to fix that in PyTorch, but it won't
be available for all the folks running older versions of PyTorch, hence
this trivial patch.

Author: StrongerXi

comfy/ops.py

@@ -41,9 +41,11 @@ def scaled_dot_product_attention(q, k, v, *args, **kwargs):
 
         SDPA_BACKEND_PRIORITY.insert(0, SDPBackend.CUDNN_ATTENTION)
 
-        @sdpa_kernel(backends=SDPA_BACKEND_PRIORITY, set_priority=True)
         def scaled_dot_product_attention(q, k, v, *args, **kwargs):
-            return torch.nn.functional.scaled_dot_product_attention(q, k, v, *args, **kwargs)
+            # Use this (rather than the decorator syntax) to eliminate graph
+            # break for pytorch < 2.9
+            with sdpa_kernel(SDPA_BACKEND_PRIORITY, set_priority=True):
+                return torch.nn.functional.scaled_dot_product_attention(q, k, v, *args, **kwargs)
 except (ModuleNotFoundError, TypeError):
     logging.warning("Could not set sdpa backend priority.")