compositor-drm: remove a stale comment

This comment became stale in:

commit 65a11e1039e7ea429ff26bdd0058bdf0efd1df2d
Author: Kristian Høgsberg <krh@bitplanet.net>
Date:   Fri Aug 3 11:30:18 2012 -0400

    compositor: Accumulate damage per plane

Now it is just misleading. Remove it.

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
1 file changed