audioflinger: Add tracing for direct tracks

Add missing calls to ATRACE for direct writes and frames ready
on direct thread.

Test: <start direct output>
      external/chromium-trace/systrace.py audio

Merged-In: Iee6ea72442f9902819628735e19cce0ba1546165
Change-Id: Iee6ea72442f9902819628735e19cce0ba1546165