Fix Gemma RMSNorm +1 offset missing on --checkpoint path

The `--checkpoint` code path skipped the Gemma-specific RMSNorm weight
adjustment (`weight + 1`). Gemma stores norm weights as deviations from
1 and computes `(1 + w) * x`, but ExecuTorch's RMSNorm computes `w * x`.
The HF download path applied the +1 offset correctly, but passing a
converted checkpoint via `--checkpoint` silently produced garbage output
from all 36+ norm layers, regardless of quantization recipe.

Author: psiddh

examples/qualcomm/oss_scripts/llama/wrappers/llm_wrappers.py

@@ -192,6 +192,19 @@ def _prepare_model(self):  # noqa: C901
                     k.replace("_orig_mod.", ""): v for k, v in state_dict.items()
                 }
 
+            if self.control_args.decoder_model in {
+                "gemma-2b",
+                "gemma2-2b",
+                "gemma3-1b",
+            }:
+                for k, v in state_dict.items():
+                    if "norm" not in k:
+                        continue
+                    # Gemma RMSNorm uses (1 + w) * x, so converted checkpoints
+                    # that haven't been offset need +1 applied here.
+                    # See https://github.com/huggingface/transformers/pull/29402
+                    state_dict[k] = v.float() + torch.ones(v.shape, dtype=torch.float32)
+
         # change to HF weight to improve the performance of RoPE in HTP backend.
         if self.config.transform_weight: