Migrate BatteryStats audio calls to oneway

The batterystats binder interfaces used by audioserver are currently
synchronous, which causes layering violations leading to threadpool
starvation in system server.

Migrate the calls used by audioserver in particular to oneway. These
calls are already void returning, and are logically async.

It is generally not recommended to mix oneway and non-oneway calls due
to unclear ordering, but migrate the three methods used by audioserver
together, and add a comment to explain. This interface is already
mixed oneway for this reason.

Fixes: 330359963
Test: dumpsys batterystats contains audio info
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:364ce02f7d46ed99e93f3f156ae1907f74de449f)
Merged-In: I7220ad5287b142821ef39d175c3bf88d4a898a43
Change-Id: I7220ad5287b142821ef39d175c3bf88d4a898a43