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

This reverts commit 81735ecb

.

The hardware needs data to follow the previous alignment, so this extra
space was not superfluous after all. Besides, this also made
v4l2-compliance's G_FMT and S_FMT tests regress.

Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
Acked-by: Tiffany Lin <tiffany.lin@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>