drm/gma500: Use drm_fb_helper_lastclose() and _poll_changed()

This driver can use drm_fb_helper_lastclose() as its .lastclose callback.
It can also use drm_fb_helper_output_poll_changed() as its
.output_poll_changed callback.

Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171205182504.41923-6-noralf@tronnes.org
diff --git a/drivers/gpu/drm/gma500/psb_drv.c b/drivers/gpu/drm/gma500/psb_drv.c
index 8f5cc1f..38d09d4 100644
--- a/drivers/gpu/drm/gma500/psb_drv.c
+++ b/drivers/gpu/drm/gma500/psb_drv.c
@@ -107,19 +107,6 @@ MODULE_DEVICE_TABLE(pci, pciidlist);
 static const struct drm_ioctl_desc psb_ioctls[] = {
 };
 
-static void psb_driver_lastclose(struct drm_device *dev)
-{
-	int ret;
-	struct drm_psb_private *dev_priv = dev->dev_private;
-	struct psb_fbdev *fbdev = dev_priv->fbdev;
-
-	ret = drm_fb_helper_restore_fbdev_mode_unlocked(&fbdev->psb_fb_helper);
-	if (ret)
-		DRM_DEBUG("failed to restore crtc mode\n");
-
-	return;
-}
-
 static int psb_do_init(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = dev->dev_private;
@@ -479,7 +466,7 @@ static struct drm_driver driver = {
 			   DRIVER_MODESET | DRIVER_GEM,
 	.load = psb_driver_load,
 	.unload = psb_driver_unload,
-	.lastclose = psb_driver_lastclose,
+	.lastclose = drm_fb_helper_lastclose,
 
 	.num_ioctls = ARRAY_SIZE(psb_ioctls),
 	.irq_preinstall = psb_irq_preinstall,