[SD] Update need_vae_encode correctly

Signed-Off-by: Gaurav Shukla <gaurav@nod-labs.com>

apps/stable_diffusion/scripts/txt2img.py

@@ -105,7 +105,7 @@ def txt2img_inf(
         args.iree_vulkan_target_triple = ""
         args.use_tuned = True
         args.import_mlir = False
-        args.img_path = ""
+        args.img_path = None
         set_init_device_flags()
         model_id = (
             args.hf_model_id

apps/stable_diffusion/src/models/model_wrappers.py

@@ -334,6 +334,8 @@ class SharkifyStableDiffusionModel:
             if args.hf_model_id == "":
                 sys.exit("Base model configuration for the custom model is missing. Use `--clear_all` and re-run.")
             print("Loaded vmfbs from cache and successfully fetched base model configuration.")
+            if not need_vae_encode:
+                return vmfbs[:3]
             return vmfbs
 
         # Step 2: