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>