Revert "ASoC: msm: Flexible period size for pcm playback"

This reverts commit 9183ff0a90d82939033563b9e6a15fc091c76ea5.
Adjust PLAYBACK_PERIOD_SIZE

This now agrees on what is defined in the HAL.
Without this, NuPlayer will sometimes behave strange and fail to fill up the buffer (while jerking the video playback)

Conflicts:
	sound/soc/msm/msm-pcm-q6.c

Change-Id: If8879a56052ce9efd56529602d3d48878191cbae