[Attention] Remove imports from vllm/attention/__init__.py (#29342)

Signed-off-by: Matthew Bonanni <mbonanni@redhat.com>

vllm/model_executor/models/chameleon.py

@@ -16,7 +16,7 @@ from transformers import (
     ChameleonVQVAEConfig,
 )
 
-from vllm.attention import Attention
+from vllm.attention.layer import Attention
 from vllm.config import CacheConfig, VllmConfig
 from vllm.config.multimodal import BaseDummyOptions
 from vllm.distributed import get_pp_group, get_tensor_model_parallel_world_size