Fix mps example for non-LLMs (#11538)

Fix broken ios app demo tests

Author: jackzhxng

examples/apple/mps/scripts/mps_example.py

@@ -138,18 +138,25 @@ def parse_args():
     if args.model_name not in MODEL_NAME_TO_MODEL:
         raise RuntimeError(f"Available models are {list(MODEL_NAME_TO_MODEL.keys())}.")
 
-    llm_config = LlmConfig()
     if args.model_name == "llama2":
+        # Building LLM example.
+        llm_config = LlmConfig()
         if args.checkpoint:
             llm_config.base.checkpoint = args.checkpoint
         if args.params:
             llm_config.base.params = args.params
         llm_config.model.use_kv_cache = True
-    model, example_inputs, _, _ = EagerModelFactory.create_model(
-        module_name=MODEL_NAME_TO_MODEL[args.model_name][0],
-        model_class_name=MODEL_NAME_TO_MODEL[args.model_name][1],
-        llm_config=llm_config,
-    )
+        model, example_inputs, _, _ = EagerModelFactory.create_model(
+            module_name=MODEL_NAME_TO_MODEL[args.model_name][0],
+            model_class_name=MODEL_NAME_TO_MODEL[args.model_name][1],
+            llm_config=llm_config,
+        )
+    else:
+        # Building non-LLM example.
+        model, example_inputs, _, _ = EagerModelFactory.create_model(
+            module_name=MODEL_NAME_TO_MODEL[args.model_name][0],
+            model_class_name=MODEL_NAME_TO_MODEL[args.model_name][1],
+        )
 
     model = model.eval()