diag: dci: Preventing unitialized stack memcpy operation

At certain point in diag driver there can be memcpy operation
for the unintialized stack. Due to uninitilization of memory
user can obatin valuable information on accessing this stack
in userspace. This patch fixes that issue.

Change-Id: I4bfcf156300132dc426dcadce325e0c76c1d0357
CRs-fixed: 565808
Signed-off-by: Katish Paran <kparan@codeaurora.org>