[media] vcodec:mediatek: Fix visible_height larger than coded_height issue in s_fmt_out

The original code add extra 32 line to visible_height.
It is incorrect, 32 line should be add to coded_height.
The purpose is that user space could calcuate real buffer size needed by using
coded_width * coded_height.
But this method will make v4l2-compliance test fail, since g_fmt != s_fmt(g_fmt)
So remove extend visible_height or coded_height, user space should just
use sizeimage to get real buffer size needed

Signed-off-by: Tiffany Lin <tiffany.lin@mediatek.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>