fix(motif): fix lambda init fn

Sync with https://huggingface.co/Motif-Technologies/Motif-2.6B/blob/main/modeling_motif.py#L366

Signed-off-by: WyldeCat <skan1543@gmail.com>

Signed-off-by: ca1207 <ca1207zzz@gmail.com>

Author: WyldeCat

vllm/model_executor/models/motif.py

@@ -236,7 +236,7 @@ def __init__(
                 ), diff_attn_err_msg
 
     def lambda_init_fn(self, depth):
-        return 0.8 - 0.6 * math.exp(-0.3 * depth)
+        return 0.8 - 0.6 * math.exp(-0.3 * (depth - 1))
 
     def forward(
         self,