Add tracing tags to vibrator

Now all somewhat time-consuming methods of the VibratorService
are surrounded by traceBegin/traceEnd blocks.
The vibration itself is surrounded with asyncTrace block.

Test: Run "systrace vibrator" and see the time consumption report.
Bug: 73000045
Change-Id: Ie6347d179cf3e0dd13dc3daf76917f3fbb870d2b