media: Revert "media: mtk-vcodec: Remove extra area allocation in an input buffer on encoding"

This reverts commit 3192b2ca.

There are indications that this patch causes problems on some
platforms due to some hardware prefetch. Reverting this patch
for now until this is better understood.

Reported-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>