audio policy service: fix spatializer locking scheme

The audio policy service should never call Spatializer controller
methods with its mutex held. This rule was only partly repected.
This CL fixes the remaining call sites.

Bug: 237833275
Test: repro steps in the bug.
Merged-In: I2a1828d9e4cd3e16a68c727ae84329c92666c6ab
Change-Id: I2a1828d9e4cd3e16a68c727ae84329c92666c6ab