ASoC: msm: qdsp6v2: Add session specific control for slowtalk

Update slowtalk control to make it session specific. Add
functionality to handle all sessions for HALs that are not session
specific.

Change-Id: Icd3ffb59ebae156ee4ca66196860e14d715ed0e4
Signed-off-by: Pradnya Chaphekar <pradnyac@codeaurora.org>