media: mtk-vcodec: replace func vidioc_try_fmt with two funcs for out/cap

The function vidioc_try_fmt has a big 'if-else' for
the capture and output cases. There is hardly any code
outside of that condition. It is therefore better to split
that functions into two different functions, one for each case.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>