Arm backend: Add model name to -llama_inputs

[mansnils]

This way other Llama variants than stories110m can be run.

cc @digantdesai @freddan80 @per @zingo @oscarandersson8218

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/10775

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❌ 1 New Failure, 2 Pending

As of commit f7e2c84 with merge base 51befee ():

NEW FAILURE - The following job has failed:

• trunk / test-llama-runner-mac (fp32, mps) / macos-job (gh)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 1

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