fix: guard configure_deep_gemm_num_sms when JIT disabled (#20868)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

python/sglang/srt/layers/deep_gemm_wrapper/entrypoint.py

@@ -122,7 +122,7 @@ def update_deep_gemm_config(gpu_id: int, server_args: ServerArgs):
 
 @contextmanager
 def configure_deep_gemm_num_sms(num_sms):
-    if num_sms is None:
+    if num_sms is None or not ENABLE_JIT_DEEPGEMM:
         yield
     else:
         original_num_sms = deep_gemm.get_num_sms()