nnpalm: refactor namespaces

Add a new namespace alpha_model under internal_onedevice, so that it
will be easier when we add beta model in a next CL.
Move v2 namesapce under internal_ondevice and rename it as
alpha_model_v2 since it doesn't apply to beta model.

Bug: b:228271213
Test: verified on a reference device
Change-Id: I0661807f5a383d75822551c4490b2a6808db587b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3649925
Reviewed-by: Rob Schonberger <robsc@chromium.org>
Commit-Queue: Jing Wang <jiwan@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1005543}
5 files changed