In #8693 the issue was fixed for par > 1 without noticing that
it was also broken for par > 1.
Given that the natural width and height only changes when par != 1,
the logic is simplified to do:
* par_n < par_d -> the height is corrected
* par_n > par_d -> the width is corrected
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8828>
37a57b57e6