ASoC : msm: Add IOCTL for Listen LookAhead Buffering

LookAhead buffering is a feature used for buffering PCM
data from codec once the successfull keyword detection is
done for a given sound model. This change defines the IOCTL
interface for LAB feature to user space. User space
can use these IOCTL to control and stop LAB.

Change-Id: I386c4855949a7b6ed0c3c12d950cd804af772f4c
Signed-off-by: Venkat Sudhir <vsudhir@codeaurora.org>