Fixes typo when indexing after self.conv1d (#580)

Original version indexes sequence to the padding, not the sequence length (and has a typo when refering self.dconv instead of self.d_conv).

Author: tdgfrost

mamba_ssm/modules/mamba2.py

@@ -230,7 +230,7 @@ def forward(self, u, seqlen=None, seq_idx=None, cu_seqlens=None, inference_param
             if causal_conv1d_fn is None or self.activation not in ["silu", "swish"]:
                 assert seq_idx is None, "varlen conv1d requires the causal_conv1d package"
                 xBC = self.act(
-                    self.conv1d(xBC.transpose(1, 2)).transpose(1, 2)[:, -(self.dconv - 1):]
+                    self.conv1d(xBC.transpose(1, 2)).transpose(1, 2)[:, :-(self.d_conv - 1)]
                 )  # (B, L, self.d_ssm + 2 * ngroups * d_state)
             else:
                 xBC = causal_conv1d_fn(