drm/i915: Make intel_dp_check_link_status() static

This function is only used in intel_dp.c since:

  commit 0e32b39cee
  Author: Dave Airlie <airlied@redhat.com>
  Date:   Fri May 2 14:02:48 2014 +1000

      drm/i915: add DP 1.2 MST support (v0.7)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_dp.c

@@ -3818,7 +3818,7 @@ go_again:
  *  3. Use Link Training from 2.5.3.3 and 3.5.1.3
  *  4. Check link status on receipt of hot-plug interrupt
  */
-void
+static void
 intel_dp_check_link_status(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);

drivers/gpu/drm/i915/intel_drv.h

@@ -1019,7 +1019,6 @@ void intel_dp_complete_link_train(struct intel_dp *intel_dp);
 void intel_dp_stop_link_train(struct intel_dp *intel_dp);
 void intel_dp_sink_dpms(struct intel_dp *intel_dp, int mode);
 void intel_dp_encoder_destroy(struct drm_encoder *encoder);
-void intel_dp_check_link_status(struct intel_dp *intel_dp);
 int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc);
 bool intel_dp_compute_config(struct intel_encoder *encoder,
 			     struct intel_crtc_state *pipe_config);