[Attention][3/n] Remove usage of deprecated `seq_lens_cpu` and...

[Attention][3/n] Remove usage of deprecated `seq_lens_cpu` and `num_computed_tokens_cpu` CommonAttentionMetadata properties (#31850)
Signed-off-by: Lucas Wilkinson <lwilkins@redhat.com>

vllm/v1/attention/backends/rocm_aiter_fa.py

@@ -337,7 +337,7 @@ class AiterFlashAttentionMetadataBuilder(
 
         query_start_loc_cpu = common_attn_metadata.query_start_loc_cpu
 
-        seq_lens = common_attn_metadata.seq_lens_cpu
+        seq_lens = common_attn_metadata.seq_lens.cpu()
 
         query_lens_cpu = query_start_loc_cpu[1:] - query_start_loc_cpu[:-1]
 
@@ -367,7 +367,7 @@ class AiterFlashAttentionMetadataBuilder(
         if num_extends > 0:
             num_extends_slice = slice(num_decodes, num_decodes + num_extends)
             query_lens_for_extend = query_lens_cpu[num_extends_slice]
-            seq_lens_for_extend = common_attn_metadata.seq_lens_cpu[num_extends_slice]
+            seq_lens_for_extend = seq_lens[num_extends_slice]
             computed_kv_lens = seq_lens_for_extend - query_lens_for_extend
             swa_metadata = None
             if self.aot_sliding_window is not None:

vllm/v1/attention/backends/rocm_attn.py

@@ -124,7 +124,7 @@ class RocmAttentionMetadataBuilder(AttentionMetadataBuilder[RocmAttentionMetadat
             prefix_kv_lens = torch.tensor(
                 [common_prefix_len], dtype=torch.int32, device=self.device
             )
-            suffix_kv_lens = common_attn_metadata.seq_lens_cpu - common_prefix_len
+            suffix_kv_lens = common_attn_metadata.seq_lens.cpu() - common_prefix_len
             suffix_kv_lens = suffix_kv_lens.to(self.device)
         else:
             cu_prefix_query_lens = None