[torch.compile] use empty tensor instead of None for profiling (#8875)

tests/kernels/test_encoder_decoder_attn.py

@@ -136,7 +136,9 @@ def _make_test_resources(test_pt: TestPoint, ) -> TestResources:
     )
     if test_pt.num_blocks is None or test_pt.num_heads is None:
         # Caller does not require a KV cache
-        return TestResources(scale, attn_backend, attn, None)
+        return TestResources(
+            scale, attn_backend, attn,
+            torch.tensor([], dtype=torch.float32, device=CUDA_DEVICE))
 
     # Construct KV cache
     kv_cache = make_kv_cache(test_pt.num_blocks,
@@ -620,7 +622,9 @@ def _run_encoder_attention_test(
     return attn.forward(packed_qkv.query,
                         packed_qkv.key,
                         packed_qkv.value,
-                        None,
+                        torch.tensor([],
+                                     dtype=torch.float32,
+                                     device=packed_qkv.query.device),
                         attn_metadata,
                         attn_type=attn_type)