[Output Switcher] Improve volume control

improve volume control to avoid volume jump when adjustment happened too
intensive.
1.When we send two requests to adjust volume, we record second(latest)
request volume change value.
2. We receive response from first request -> this will cause volume bar
   jump, so in this change will ignore this update
3. We receive second response, we'll accept it cause value match.

Bug: 291754047
Test: Verify on device by adjust volume twice in very short period, and
no volume bar jump situation happened.
Change-Id: I6871adad229281076414e02d5002c04d43fc3e32