Update README and weights saving imports

Author: eagarvey-amd

models/turbine_models/custom_models/torchbench/README.md

@@ -32,5 +32,5 @@ cd ..
 ### Export and compile
 
 ```shell
-python ./export.py --model_id=All --target=gfx942 --device=hip --compile_to=vmfb --accuracy --inference
+python ./export.py --target=gfx942 --device=rocm --compile_to=vmfb --performance --inference --precision=fp16 --float16 --external_weights=safetensors --external_weights_dir=./torchbench_weights/
 ```

models/turbine_models/custom_models/torchbench/utils.py

@@ -4,6 +4,7 @@
 import os
 import safetensors
 import safetensors.numpy as safe_numpy
+import safetensors.torch as safe_torch
 import re
 import glob
 
@@ -461,7 +462,7 @@ def save_external_weights(
                 mod_params = vae_params
             if external_weight_file and not os.path.isfile(external_weight_file):
                 if not force_format:
-                    safetensors.torch.save_file(mod_params, external_weight_file)
+                    safe_torch.save_file(mod_params, external_weight_file)
                 else:
                     for x in mod_params.keys():
                         mod_params[x] = mod_params[x].numpy()