Only the intel_crtc->active is accurate at the point where we wish to
perform WM computations, so use it instead of crtc->enabled.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>