qbt1000: Fix for incorrect buffer size check and integer overflow

Fix an incorrect buffer size check which might have caused integer
overflow.

CRs-Fixed: 2045285
Change-Id: I3b5b996c7405f51b488d6cbda31c81a9a9905f23
Signed-off-by: Abir Ghosh <abirg@codeaurora.org>
Signed-off-by: Kota Priyanka <kotap@codeaurora.org>