The V4L2 driver does not actually have an associated DRM device at all, so
users work around the requirement by giving libva an unrelated display-only
device instead (which is fine, because it doesn't actually do anything with
that device). This was broken by bc9b6358fb7315c0173de322472641766f6289da
forcing a render node, because the display-only device did not have an
associated render node to use. Fix that by just passing through the
original non-render DRM fd if we can't find a render node.
Reported-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Tested-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
303d252a4b