drm/i915/bxt: Set oscaledcompmethod to enable scale value

drm/i915/bxt: Set oscaledcompmethod to enable scale value

Bspec update tells that we have to enable oscaledcompmethod instead of
ouniqetrangenmethod for enabling scale value during swing programming.

v2: Adding back 'don't care' values to bxt_ddi_translations_dp and add
error message if ouniquetrangemethod was set (Imre)

Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>(v1)
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>