ASoC: msm: Add MultiKeyword support for Listen

Listen is a Voice activation and recognition feature.
Currently Listen feature supports recognition of single
keyword for a given session. This change adds support
for MultiKeyword detection for each Listen session.

Change-Id: I614dcbe101eeb42e8420496d39edace74010f5c8
Signed-off-by: Venkat Sudhir <vsudhir@codeaurora.org>