drm: move drm vblank initialization/cleanup to driver load/unload

drm vblank initialization keeps track of the changes in driver-supplied
frame counts across vt switch and mode setting, but only if you let it by
not tearing down the drm vblank structure.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 3ab1e9c..996097a 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -305,6 +305,8 @@
 		return;
 	}
 
+	drm_vblank_cleanup(dev);
+
 	drm_lastclose(dev);
 
 	if (drm_core_has_MTRR(dev) && drm_core_has_AGP(dev) &&