drm/i915: Return correct EDP voltage swing table for 0.85V

For 0.85V cnl_get_buf_trans_edp() returns the DP table, instead of EDP.
Use the correct table.

The error was pointed out by this clang warning:

drivers/gpu/drm/i915/intel_ddi.c:392:39: warning: variable
  'cnl_ddi_translations_edp_0_85V' is not needed and will not be emitted
  [-Wunneeded-internal-declaration]
    static const struct cnl_ddi_buf_trans cnl_ddi_translations_edp_0_85V[] = {

Fixes: cf54ca8b

 ("drm/i915/cnl: Implement voltage swing sequence.")
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170717195854.192139-1-mka@chromium.org
(cherry picked from commit 50946c89

)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>