[Bugfix] Mamba2 remove bugged initial state condition in chunk scan (#22034)

Signed-off-by: Chih-Chieh-Yang <7364402+cyang49@users.noreply.github.com>

vllm/model_executor/layers/mamba/ops/ssd_chunk_scan.py

@@ -476,15 +476,8 @@ def _chunk_scan_fwd(
             # with initial states, we need to take care of how
             # seq_idx crosses the boundaries
             assert batch == 1, "chunk scan only supports initial states with batch 1"
-
-            if initial_states.shape[0] == 1:
-                # no in this case no point to use initial states
-                initial_states = None
-            else:
             assert chunk_indices is not None and chunk_offsets is not None, \
-                    (
                 "chunk_indices and chunk_offsets should have been set"
-                    )
         else:
             chunk_indices, chunk_offsets = None, None
     else: