ASoC: msm: add work queue to make sure MCLK is on.

In 8916 target to access digital codec registers there
is a requirement to make sure the MCLK is enabled otherwise
apps will end up in un authorized access and crash.

To achieve this a work queue is added and scheduled before
any read or write access is attempted and this work queue
will make sure the MCLK is enabled for 3 seconds and gets
deleted when the session is active.

Also the MCLK enable event is triggered now from session start
and stop.

CRs-Fixed: 638024
Change-Id: If1b608d5728dc35d7f16635fe5996fa08e693185
Signed-off-by: Santosh Mardi <gsantosh@codeaurora.org>