Spatializer: fix deadlock in onSupportedLatencyModesChanged

The Spatializer controller must not call AudioFlinger methods from
AudioFlinger callbacks to avoid risks of deadlock with AudioFlinger or
AudioFlinger threads mutexes.

Process the onSupportedLatencyModesChanged() callbakc in the handler
thread instead of synchronously

Bug: 239540985
Test: repro steps in bug
Change-Id: Ia7af5631f26a72adce6ef8dc762196ae58d3f695