coverity: fix check_after_deref
coverity: fix check_after_deref

- /va/x11/dri2_util.c:
> libva-1.8.3/va/x11/dri2_util.c:218: check_after_deref: Null-checking
> "device_name" suggests that it may be null, but it has already been
> dereferenced on all paths leading to the check.

Signed-off-by: Victor Toso <39b7599ff73bbf5db531748ba5250f21fa7120ff@redhat.com>

01org/libva-cros,01org/libva-cros,01org/libva-cros