[Bugfix] Fix flashinfer ar+norm kernel not available issue (#29960)

Signed-off-by: elvischenv <219235043+elvischenv@users.noreply.github.com>

vllm/compilation/fix_functionalization.py

@@ -104,7 +104,8 @@ class FixFunctionalizationPass(VllmInductorPass):
                 mutated_args = {1: "result"}
                 self.defunctionalize(graph, node, mutated_args)
             elif (
-                at_target
+                hasattr(torch.ops.vllm, "flashinfer_trtllm_fused_allreduce_norm")
+                and at_target
                 == torch.ops.vllm.flashinfer_trtllm_fused_allreduce_norm.default
             ):
                 mutated_args = {