fix no sequence length models error (#27522)

* fix no sequence length models error

* block size check

---------

Co-authored-by: Adam Louly <adamlouly@microsoft.com@orttrainingdev9.d32nl1ml4oruzj4qz3bqlggovf.px.internal.cloudapp.net>

examples/pytorch/language-modeling/run_clm.py

@@ -510,7 +510,10 @@ def main():
                 f"The tokenizer picked seems to have a very large `model_max_length` ({tokenizer.model_max_length}). "
                 f"Using block_size={min(1024, max_pos_embeddings)} instead. You can change that default value by passing --block_size xxx."
             )
+            if max_pos_embeddings > 0:
                 block_size = min(1024, max_pos_embeddings)
+            else:
+                block_size = 1024
     else:
         if data_args.block_size > tokenizer.model_max_length:
             logger.warning(