drm/virtio: fix NULL pointer dereference in virtiogpuconngetmodes
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v4.9.318 by commit e0828456578cc8ba0a69147f7ae3428392eec287. For more details please see the references link.