gma500: mark oaktrail_backlight_init() as static

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/gma500/oaktrail_device.c

@@ -141,7 +141,7 @@ static const struct backlight_ops oaktrail_ops = {
 	.update_status  = oaktrail_set_brightness,
 };
 
-int oaktrail_backlight_init(struct drm_device *dev)
+static int oaktrail_backlight_init(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = dev->dev_private;
 	int ret;