Make Audio wakelock names less unique.

These wakelocks now show up in the client process, where they
might cause wakelock overflows if AudioFlinger threads die often.

The client process should be agnostic of audio flinger threading,
so don't make the wakelock names rely on audioflinger thread names.

Wakelock names now depend only on the audio flinger thread type, and
not the ID itself.

bug: 11200551

Change-Id: Ia1f71b569cb7502d617b77596abc245f461a6ec0