ASoC: msm8974: Audio ocmem driver changes to fix playback issues

Fix issues when alloc grow, shrink requests received while display
off/on. Add return statement to the audio/voice workqueue for the safe
exit.

Change-Id: Ifda7823f68ef0f26b9fe781c4c509c7633291169
CRs-fixed: 404445
Signed-off-by: Phani Kumar Uppalapati <phanik@codeaurora.org>