OMAP: DSS2: move set/get_wss()

Move set/get_wss() from omap_dss_device to omap_dss_driver.

This is part of a larger patch-set, which moves the control from omapdss
driver to the display driver.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>
diff --git a/drivers/video/omap2/dss/display.c b/drivers/video/omap2/dss/display.c
index 29ec5a4..351c8ab 100644
--- a/drivers/video/omap2/dss/display.c
+++ b/drivers/video/omap2/dss/display.c
@@ -247,10 +247,10 @@
 	struct omap_dss_device *dssdev = to_dss_device(dev);
 	unsigned int wss;
 
-	if (!dssdev->get_wss)
+	if (!dssdev->driver->get_wss)
 		return -ENOENT;
 
-	wss = dssdev->get_wss(dssdev);
+	wss = dssdev->driver->get_wss(dssdev);
 
 	return snprintf(buf, PAGE_SIZE, "0x%05x\n", wss);
 }
@@ -262,7 +262,7 @@
 	unsigned long wss;
 	int r;
 
-	if (!dssdev->get_wss || !dssdev->set_wss)
+	if (!dssdev->driver->get_wss || !dssdev->driver->set_wss)
 		return -ENOENT;
 
 	if (strict_strtoul(buf, 0, &wss))
@@ -271,7 +271,7 @@
 	if (wss > 0xfffff)
 		return -EINVAL;
 
-	r = dssdev->set_wss(dssdev, wss);
+	r = dssdev->driver->set_wss(dssdev, wss);
 	if (r)
 		return r;