This define hasn't been used since:
commit 652c393a33
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date: Mon Aug 17 13:31:43 2009 -0700
drm/i915: add dynamic clock frequency control
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>