Use hard-coded constants previously computed at runtime within a loop in
`ComputeAndPostProcessLpcCoefficients`.
Note that the `RnnVadTest.LpResidualPipelineBitExactness` unit test
is still passing.
Bug: webrtc:10480
Change-Id: Iaec178c56937449c3fe9af881354d19cc8c47c7d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/189961
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32462}