drm/i915/skl: Program the DDI buffer translation tables

A couple of things have changed compared to Broadwell:
  - Entry 9 is used for eDP
  - No more FDI

v2: Update the translation values to latest specs.
v3: Rebase on top of the BDW HDMI translation patch
v4: Remove the low voltage edp tables,
    Rebase on top of the patch not writing the HDMI entry on eDP/FDI
    DDIs (Satheesh, Paulo).
v5: Apply the / 2 fix for the number of HDMI entries (Satheesh)
v6: Rebase on top of Jani's clean up for the DDI_BUF_TRANS tables
v7: Restore the commit message that was mangled by error

Reviewed-by: Thomas Wood <thomas.wood@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>