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>