drm: Fix kerneldoc and remove unused struct member in self_refresh helper

Artifacts of previous revisions.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link to v1: https://patchwork.freedesktop.org/patch/msgid/20190917200443.64481-1-sean@poorly.run
Link: https://patchwork.freedesktop.org/patch/msgid/20190918200734.149876-1-sean@poorly.run

Changes in v2:
- None

drivers/gpu/drm/drm_self_refresh_helper.c

@@ -53,7 +53,6 @@
 struct drm_self_refresh_data {
 	struct drm_crtc *crtc;
 	struct delayed_work entry_work;
-	struct drm_atomic_state *save_state;
 	unsigned int entry_delay_ms;
 };
 

include/drm/drm_crtc.h

@@ -1108,7 +1108,7 @@ struct drm_crtc {
 	/**
 	 * @self_refresh_data: Holds the state for the self refresh helpers
 	 *
-	 * Initialized via drm_self_refresh_helper_register().
+	 * Initialized via drm_self_refresh_helper_init().
 	 */
 	struct drm_self_refresh_data *self_refresh_data;
 };