Added kwarg support for dynamo.compile

Author: cehongwang

py/torch_tensorrt/dynamo/_compiler.py

@@ -176,6 +176,8 @@ def compile(
         else:
             make_refitable = kwargs["refit"]
 
+    if kwarg_inputs is None:
+        kwarg_inputs = {}
     engine_capability = EngineCapability._from(engine_capability)
 
     if torch_executed_modules is not None and torch_executed_modules: