Remove drift compensator

Drift compensation is better done by the actual sensor, as it has the
knowledge of the best method to do so. For example, some sensors don't
suffer from drift at all.

This change replaces the drift compensation with a much simpler module
which only takes care of biasing (for recentering purposes).

Test: atest --host libheadtracking-test
Test: Manual verification of spatial audio with head-tracking.
Change-Id: I50ad8f53a6d7016bb8f75772702b35634adbc413