aosp-frameworks-ml-nn: fix vendor hal loading

With the implementation of multi-HAL loading (crrev.com/c/3007637), it
actually breaks the ability to load vendor HALs (ie, intel-nnhal).

This CL cleans up the dependencies and structure slightly to allow the
installed libvendor-nnhal.so from other packages to override the default
one.

BUG=b:196007189
TEST=USE=vendor-nnhal emerge-volteer aosp-frameworks-ml-nn

Change-Id: I7e0224ceca8b8904cea37996733e40b040004ad2
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/frameworks/ml/+/3083669
Tested-by: Jim Pollock <[email protected]>
Auto-Submit: Jim Pollock <[email protected]>
Commit-Queue: Jim Pollock <[email protected]>
Reviewed-by: Michael Olney <[email protected]>
2 files changed