drm/i915: Fix iboost setting for SKL Y/U DP DDI buffer translation entry 2

drm/i915: Fix iboost setting for SKL Y/U DP DDI buffer translation entry 2

The spec was recently fixed to have the correct iboost setting for the
SKL Y/U DP DDI buffer translation table entry 2. Update our tables
to match.

Cc: David Weinehall <david.weinehall@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470140517-13011-1-git-send-email-ville.syrjala@linux.intel.com
Cc: stable@vger.kernel.org
Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>