camera_v1/v2: Fix multiple JPEG integer overflow issues

Fixes multiple issues in the gemini and jpeg 1.0 cores when parsing
hw commands:

1. Fixes integer overflow issue when calculating the length of the
command buffer.
2. Fixes signedness issue with the command count.

CRs-fixed: 504640
Signed-off-by: Kamen Kirov <kkirov@codeaurora.org>
Change-Id: I0a701c67b93cc97af119b31639db699e5ae58489