drm/i915/dvo/ch7xxx: Fix suspend/resume

drm/i915/dvo/ch7xxx: Fix suspend/resume

Poke a few more bits into the ch7xxx to make
it output a picture after being reset during S3.

In particular we need to set the input buffer select (IBS),
and enable VGA vsync output on the BCO pin. Selecting
VGA hsync on the c/h sync pin doesn't actually seem necessary
on my ADD card at least, but the BIOS selects it so why not.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221122120825.26338-2-ville.syrjala@linux.intel.com
Acked-by: Jani Nikula <jani.nikula@intel.com>