msm: vidc: Ensure size of the data available before typecasting

Ensure the available data size with in the packet before type
casting from smaller data type to larger data type in order
to avoid information leak or packet out of boundary access.

Change-Id: I8614a8b3f930c87af8aa49f77ea9d768a73ea203
Signed-off-by: Priyanka Gujjula <pgujjula@codeaurora.org>