diag: dci: Add missing length check before parsing the buffer

Missing check against a structure is added to prevent possible
out of bound access while processing dci packet response.

CRs-Fixed: 2434612
Change-Id: I32c83dcc70bcf6465723be669d23e9f523e82755
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>