ASoC: msm: qdsp6v2: enable lab if keyword is detected

When LAB(Look ahead buffering) is enabled after keyword detection,
userspace will capture the PCM data for a pre-determined time once
keyword is detected. Once time elapses it will issue stop lab. If
keyword is detected again userspace module will read the PCM again.
Currently driver was not restarting the LAB once a stop is issued and
keyword is detected after stop.
This change will ensure that LAB will be started after keyword
detection.

Change-Id: Ie99ebbefe2429f026d6e701b62c58583dff03bde
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>