qcrypto: protect potential integer overflow.

Adding user passed parameters without check might
lead to Integer overflow and unpredictable system
behaviour.

Change-Id: Iaf8259e3c4a157e1790f1447b1b62a646988b7c4
Signed-off-by: Neeraj Soni <neersoni@codeaurora.org>
Signed-off-by: Zhen Kong <zkong@codeaurora.org>