Roll back hyena_mixer diffs

Signed-off-by: John St. John <jstjohn@nvidia.com>

Author: jstjohn

bionemo-recipes/recipes/evo2_megatron/src/bionemo/evo2/models/megatron/hyena/hyena_mixer.py

@@ -119,7 +119,9 @@ def __init__(
         self.fast_conv_mixer = self.hyena_config.fast_conv_mixer
 
         self.use_subquadratic_ops = self.transformer_config.use_subquadratic_ops
-        self.use_fused_b2b_causal_conv1d = self.use_subquadratic_ops
+        # TODO: Re-enable B2BCausalConv1dModule for short/medium Hyena layers once
+        # subquadratic-ops updates it to support causal_conv1d 1.6+ semantics.
+        self.use_fused_b2b_causal_conv1d = False
 
         # Per attention head and per partition values.
         assert torch.distributed.is_initialized()