fix condition

Signed-off-by: fsx950223 <fsx950223@outlook.com>

Author: fsx950223

vllm/v1/attention/backends/triton_attn.py

@@ -310,7 +310,8 @@ def forward(
         key_cache, value_cache = kv_cache.unbind(1)
 
         if (
-            self.kv_sharing_target_layer_name is None
+            self.attn_type == AttentionType.DECODER
+            and self.kv_sharing_target_layer_name is None
             and key is not None
             and value is not None
         ):