[Bluetooth] - Fix for checking proper user-supplied buffers

During patch download of devices, size validations & zero alloc
the buffers to ensure values passed are in range

CRs-fixed: 2084692
Change-Id: Ie1cd76fe68766d6d12d7262202e48c18ebe42274
Signed-off-by: Balvinder Singh <bpsingh@codeaurora.org>
Signed-off-by: Yasir Malik <ymalik@codeaurora.org>