drm/i915: Fix CRT force detect on Cougarpoint

To make CRT force detect reliable on Cougarpoint, we need to
disable DAC before force detect, and restore back when trigger
is completed.

Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
1 file changed