Fix jni_layer_llama.cpp generate_from_pos missing return

[larryliu0820]

Summary: Fix the issue on #11952 where we are missing a return in generate_from_pos()

Reviewed By: GregoryComer

Differential Revision: D77456146

[pytorch-bot]

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❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• VolumeLimitExceeded Issue for linux.2xlarge and linux.4xlarge

❌ 2 New Failures

As of commit d3a3bff with merge base 85b91a4 ():

NEW FAILURES - The following jobs have failed:

• pull / unittest / linux / linux-job (gh)
  backends/xnnpack/test/ops/test_gelu.py::TestGelu::test_fp16_gelu
• pull / unittest-editable / linux / linux-job (gh)
  backends/xnnpack/test/ops/test_exp.py::TestExp::test_fp16_exp

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This pull request was exported from Phabricator. Differential Revision: D77456146

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