xf86: Disable unused crtc functions when a lease is revoked

This fixes 'non-desktop' displays staying powered on after their lease
has been revoked.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111620
Cc: Keith Packard <keithp@keithp.com>
Signed-off-by: Andres Rodriguez <andresx7@gmail.com>