drm/nouveau: off by one in nouveau_drm_vblank_enable()

The test here should be ">= ARRAY_SIZE()" instead of "> ARRAY_SIZE()".
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_drm.c

@@ -93,7 +93,7 @@ nouveau_drm_vblank_enable(struct drm_device *dev, int head)
 	struct nouveau_drm *drm = nouveau_drm(dev);
 	struct nouveau_disp *pdisp = nouveau_disp(drm->device);
 
-	if (WARN_ON_ONCE(head > ARRAY_SIZE(drm->vblank)))
+	if (WARN_ON_ONCE(head >= ARRAY_SIZE(drm->vblank)))
 		return -EIO;
 	WARN_ON_ONCE(drm->vblank[head].func);
 	drm->vblank[head].func = nouveau_drm_vblank_handler;