drm/i915: Turn off hsync and vsync on ADPA when disabling crt

commit f40ebd6b upstream.

According to PRM we need to disable hsync and vsync even though ADPA is
disabled. The previous code did infact do the opposite so we fix it.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=56359


Tested-by: max <manikulin@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>