msm: vidc: Change platform to enable internal size calculation

Currently for internal size calculation is disabled by using
AR50 as platform type. Change this to IRIS2. However, we still
want to disable this feature hence don't call this function
for both encoder and decoder.

Change-Id: I70b589c88c80b6263fbdeca8d0975d6eea1e8ae1
Signed-off-by: Vaibhav Deshu Venkatesh <vdeshuve@codeaurora.org>