qseecom: Add boundary checks for offset within message.

Qseecom driver does not have boundary checks for offset within the
message. So this patch add checks to validate the offsets sent by
client to modify data within the command request message and it
should not exceed the memory allocated for that message.

Change-Id: I29bfbdc154eebb4f3f4bfbb31789562e37fa5886
Signed-off-by: Mona Hossain <mhossain@codeaurora.org>
Signed-off-by: Mallikarjuna Reddy Amireddy <mamire@codeaurora.org>