OMAP: DSS2: move get_resolution()

Move get_resolution() 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/venc.c b/drivers/video/omap2/dss/venc.c
index 4e6bd1d..65514f0 100644
--- a/drivers/video/omap2/dss/venc.c
+++ b/drivers/video/omap2/dss/venc.c
@@ -459,6 +459,8 @@
 	.suspend	= venc_panel_suspend,
 	.resume		= venc_panel_resume,
 
+	.get_resolution	= omapdss_default_get_resolution,
+
 	.driver         = {
 		.name   = "venc",
 		.owner  = THIS_MODULE,