VAAPI: Take more care when probing filters

- Don't try to access the image pitches when vaDeriveImage produce an error
- Don't try to delete an image_id that was not setup properly before
- Only continue checking when no check was false yet

This fixes a segfault on machines that don't support vaDeriveImage, like our fglrx friends :-)
that can easily break in the future because it is no good indicator if the image was created.