fix MLATokenToKVPoolHost get_size_per_token bug (#5161)

Co-authored-by: AniZpZ <zhuangsen.zp@antgroup.com>

python/sglang/srt/mem_cache/memory_pool.py

@@ -879,7 +879,12 @@ class MLATokenToKVPoolHost(HostKVCache):
         self.qk_rope_head_dim = self.device_pool.qk_rope_head_dim
         self.layer_num = self.device_pool.layer_num
 
-        return (self.kv_lora_rank + self.qk_rope_head_dim) * 1 * self.dtype.itemsize
+        return (
+            (self.kv_lora_rank + self.qk_rope_head_dim)
+            * 1
+            * self.dtype.itemsize
+            * self.layer_num
+        )
 
     def init_kv_buffer(self):
         return torch.empty(