virtio: get_features() can fail

Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/input/virtio-input.c b/hw/input/virtio-input.c
index 7f5b8d6..7b25d27 100644
--- a/hw/input/virtio-input.c
+++ b/hw/input/virtio-input.c
@@ -166,7 +166,8 @@
     virtio_notify_config(vdev);
 }
 
-static uint64_t virtio_input_get_features(VirtIODevice *vdev, uint64_t f)
+static uint64_t virtio_input_get_features(VirtIODevice *vdev, uint64_t f,
+                                          Error **errp)
 {
     return f;
 }