drm/i915: Remove unused "ret" variable.

Just a small clean-up with no functional change, only
removing a variable that is never actually used.

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: <nathan.d.ciobanu@linux.intel.com>
Reviewed-by: Nathan Ciobanu <nathan.d.ciobanu@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180719234217.7855-1-rodrigo.vivi@intel.com

drivers/gpu/drm/i915/intel_dp_mst.c

@@ -263,7 +263,6 @@ static void intel_mst_enable_dp(struct intel_encoder *encoder,
 	struct intel_dp *intel_dp = &intel_dig_port->dp;
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 	enum port port = intel_dig_port->base.port;
-	int ret;
 
 	DRM_DEBUG_KMS("active links %d\n", intel_dp->active_mst_links);
 
@@ -274,9 +273,9 @@ static void intel_mst_enable_dp(struct intel_encoder *encoder,
 				    1))
 		DRM_ERROR("Timed out waiting for ACT sent\n");
 
-	ret = drm_dp_check_act_status(&intel_dp->mst_mgr);
+	drm_dp_check_act_status(&intel_dp->mst_mgr);
 
-	ret = drm_dp_update_payload_part2(&intel_dp->mst_mgr);
+	drm_dp_update_payload_part2(&intel_dp->mst_mgr);
 	if (pipe_config->has_audio)
 		intel_audio_codec_enable(encoder, pipe_config, conn_state);
 }