nuplayer: Fix audio glitch heard in non-offload path

During ringtone preview glitch is heard at the beginning of
the playback. The issue happens with any use case that is
associated with deep buffer path.

NuPlayerRenderer waits before draining the buffer queue
for half of the duration of pending frames with audio sink.
During playback start NuPlayerRenderer fills up the
entire shared memory of AudioTrack i.e. 160msec and sleeps for 80msec
before the next drain attempt. If cold start latency that includes
opening driver, configuring DSP, etc.. is more than 80msec, the next
drain attempt will be delayed by yet another 80msec. During this 80msec
delay, if DSP starts rendering all the data in the shared memory
will be consumed very quickly. This is assuming the buffering
in the kernel and DSP is more than 160msec. This case is seen as an
AudioTrack underrun by AudioFlinger because of which silence is inserted
until the next buffer is written by NuPlayerRender.

Fix the issue by reducing the delay equal to a buffer duration between
two drain attempts.

CRs-Fixed: 777860
Change-Id: I8cb8cd56942ca939bf4ab950deb57fa65a77cead