drm/i915: Remove useless eDP check from intel_ddi_pre_enable_dp()

intel_edp_panel_on() will itself do the is_edp() check, so the caller
doesn't have to bother. Pre-DDI code doesn't bother, so let's follow the
same approach for DDI.
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010121207.570-7-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/intel_ddi.c

@@ -2171,7 +2171,7 @@ static void intel_ddi_pre_enable_dp(struct intel_encoder *encoder,
 
 	intel_dp_set_link_params(intel_dp, link_rate, lane_count,
 				 link_mst);
-	if (encoder->type == INTEL_OUTPUT_EDP)
+
 	intel_edp_panel_on(intel_dp);
 
 	intel_ddi_clk_select(encoder, pll);