drm/i915/skl: Only use the 800mV+2bB HDMI translation entry

This translation entry was updated after electrical validation by the hw
team. The other entries are removed from existence as they aren't
validated and because the sole use of a certain type of level shifter
for SKL products is anticipated.

v2: Remove all the other entries and force the use of the 800mv+2dB
    config (Sonika)

Suggested-by: Sonika Jindal <sonika.jindal@intel.com>
Cc: Sonika Jindal <sonika.jindal@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Sonika Jindal <sonika.jindal@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>