nn: remove unnecessary types

These may have been needed earlier in our port but are not needed now.
Removing to reduce drift with upstream.

BUG=b:165801983
TEST=FEATURES=test emerge-betty aosp-frameworks-ml-nn

Change-Id: I75e2e875c65a25eb3afbc4ec8c8133db94426ba8
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/frameworks/ml/+/2387860
Tested-by: Jim Pollock <jmpollock@chromium.org>
Auto-Submit: Jim Pollock <jmpollock@chromium.org>
Commit-Queue: Stuart Langley <slangley@chromium.org>
Reviewed-by: Stuart Langley <slangley@chromium.org>