The return type of exec_lookup() is struct nvkm_output *, so it should
return NULL rather than 0.
Signed-off-by: NThierry Reding <treding@nvidia.com>
Reviewed-by: NEmil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: NBen Skeggs <bskeggs@redhat.com>