diag: dci: Fix possible memory leak

Currently, whenever new dci client registers, diag
allocates memory from kernel and free it during
de-initialization. For one of the buffer, it is not
freeing the memory which will lead to memory leak.
This patch takes care of possible memory leak.

Change-Id: Ie50b4a549c249375f93962a5b6b20d614943f1aa
Signed-off-by: Mohit Aggarwal <maggarwa@codeaurora.org>