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/mga/mga_dma.c b/drivers/gpu/drm/mga/mga_dma.c
index c1d12dbf..b49c5ff 100644
--- a/drivers/gpu/drm/mga/mga_dma.c
+++ b/drivers/gpu/drm/mga/mga_dma.c
@@ -396,6 +396,7 @@
 int mga_driver_load(struct drm_device * dev, unsigned long flags)
 {
 	drm_mga_private_t *dev_priv;
+	int ret;
 
 	dev_priv = drm_alloc(sizeof(drm_mga_private_t), DRM_MEM_DRIVER);
 	if (!dev_priv)
@@ -415,6 +416,13 @@
 	dev->types[7] = _DRM_STAT_PRIMARY;
 	dev->types[8] = _DRM_STAT_SECONDARY;
 
+	ret = drm_vblank_init(dev, 1);
+
+	if (ret) {
+		(void) mga_driver_unload(dev);
+		return ret;
+	}
+
 	return 0;
 }