headless: fix the output refresh rate

60 millihertz is a bit low, let's make it 60 Hz as it was supposed to
be.

When the new repaint scheduling algorithm gets implemented, this
fixes 'make check' taking almost 3 minutes instead of the normal 3
seconds, when running with 7 millisecond repaint window.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniels@collabora.com>
1 file changed