drm/i915/kbl: Use propper ddi buffer translation table for Kabylake ULT and ULX.

Let's introduce ULT and ULX Kabylake definitions and start
using it for a propper DDI buffer translation.

v2: Remove extra white space. (Paulo)

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>