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: I68cfc4d856e9c0944c3af6c350d3fd690fd3401e