AudioFlinger: Update IAudioFlinger overrides

Add const as appropriate.
Declare as final for performance optimization.

Test: atest AudioTrackTest AudioRecordTest
Test: Camera YouTube
Bug: 291319167
Merged-In: I138fdedd27f7acba02214afd973f52a871ac1204
Change-Id: I138fdedd27f7acba02214afd973f52a871ac1204
5 files changed