virtio-gpu: use VIRTIO_GPU_RESOURCE_FLAG_Y_0_TOP

It's part of Linux headers for a while now.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

hw/display/virtio-gpu-virgl.c

@@ -175,7 +175,7 @@ static void virgl_cmd_set_scanout(VirtIOGPU *g,
         virgl_renderer_force_ctx_0();
         dpy_gl_scanout_texture(
             g->parent_obj.scanout[ss.scanout_id].con, info.tex_id,
-            info.flags & 1 /* FIXME: Y_0_TOP */,
+            info.flags & VIRTIO_GPU_RESOURCE_FLAG_Y_0_TOP,
             info.width, info.height,
             ss.r.x, ss.r.y, ss.r.width, ss.r.height);
     } else {