drm/i915: Reject >9 ddi translation entried if port != A/E on SKL

Only DDI A and E support 10 translation entries in DP mode. For the
other ports the tenth entry is reserved for HDMI.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449597590-6971-9-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>