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
Merged-In: I94172e379354ec3418321b8151e6182cec2e886c
Change-Id: I94172e379354ec3418321b8151e6182cec2e886c