msm: audio: qdsp6v2: Zero the cfg stack var

Write zeroes into the stack variable cfg to ensure
no previously written stack data is sent to
user-space.

Change-Id: Iea124d2528ed56d93e2a000027ff8bc30414d3fd
CRs-Fixed: 551574
Signed-off-by: Kenneth Westfield <kwestfie@codeaurora.org>
ASoC: msm: qdsp6v2: Copy frame data based on frame length

Copying data based on count will result in copying
uninitialized data to userspace which can potentially
disclose sensitive data. Fix by copying data based on
frame instead.

CRs-Fixed: 552528, 552531
Change-Id: I307b285ef2aefe00b953cf650582e9ff7e03ceb1
Signed-off-by: Shiv Maliyappanahalli <smaliyap@codeaurora.org>