drm/i915: Make intel_unpin_fb_obj() static

This function is not used outside of intel_display.c since;

  commit cf4c7c12
  Author: Matt Roper <matthew.d.roper@intel.com>
  Date:   Thu Dec 4 10:27:42 2014 -0800

      drm/i915: Make all plane disables use 'update_plane' (v5)
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -2287,7 +2287,7 @@ intel_pin_and_fence_fb_obj(struct drm_plane *plane,
 	return ret;
 }
 
-void intel_unpin_fb_obj(struct drm_i915_gem_object *obj)
+static void intel_unpin_fb_obj(struct drm_i915_gem_object *obj)
 {
 	WARN_ON(!mutex_is_locked(&obj->base.dev->struct_mutex));
 

drivers/gpu/drm/i915/intel_drv.h

@@ -934,7 +934,6 @@ void intel_release_load_detect_pipe(struct drm_connector *connector,
 int intel_pin_and_fence_fb_obj(struct drm_plane *plane,
 			       struct drm_framebuffer *fb,
 			       struct intel_engine_cs *pipelined);
-void intel_unpin_fb_obj(struct drm_i915_gem_object *obj);
 struct drm_framebuffer *
 __intel_framebuffer_create(struct drm_device *dev,
 			   struct drm_mode_fb_cmd2 *mode_cmd,