Don't update info's size with the VA image reported data size for single plane
images, since drivers might allocate bigger space than the strictly required to
store the image, but when we dump the buffer as is (using filesink, for example)
the produced stream is corrupted. For multi-plane images video meta is required
to read/write them.
We updated info's size because gstreamer-vaapi did it too, but the reason to
update it there was for uploading and rendering surfaces (commit c698a015).
Furthermore, this patch adds an error message if the allocated data size for the
image by the driver is lesser than the expected because it would be a buggy
driver.
Fixes: #2959
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5308>
4c5e17308e