drm: export tile-group functions

Normally these are called from within drm core, from the EDID parsing
code.  But for dual-dsi in some drivers (at least drm/msm) we need to
call these from the driver.  So they should be exported.
Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_crtc.c

@@ -5599,6 +5599,7 @@ struct drm_tile_group *drm_mode_get_tile_group(struct drm_device *dev,
 	mutex_unlock(&dev->mode_config.idr_mutex);
 	return NULL;
 }
+EXPORT_SYMBOL(drm_mode_get_tile_group);
 
 /**
  * drm_mode_create_tile_group - create a tile group from a displayid description
@@ -5637,3 +5638,4 @@ struct drm_tile_group *drm_mode_create_tile_group(struct drm_device *dev,
 	mutex_unlock(&dev->mode_config.idr_mutex);
 	return tg;
 }
+EXPORT_SYMBOL(drm_mode_create_tile_group);