msm: audio: initialize the structure before sending to user space

If uninitialzied structure is passed from kernel to user space, it
may contain contain sensitive information that will be leaked.

CRs-fixed: 550054
Change-Id: I2e93ed20898e0dc804aa1ffe6791f0cfddfba288
Signed-off-by: Fred Oh <fred@codeaurora.org>