drm/nouveau: fix some error-path leaks in fbcon handling code

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_fbcon.c

@@ -385,6 +385,7 @@ out_unlock:
 	mutex_unlock(&dev->struct_mutex);
 	if (chan)
 		nouveau_bo_vma_del(nvbo, &fbcon->nouveau_fb.vma);
+	nouveau_bo_unmap(nvbo);
 out_unpin:
 	nouveau_bo_unpin(nvbo);
 out_unref: