OMAP: DSS2: move get_recommended_bpp()

Move get_recommended_bpp() 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 65514f0..d13071d 100644
--- a/drivers/video/omap2/dss/venc.c
+++ b/drivers/video/omap2/dss/venc.c
@@ -460,6 +460,7 @@
 	.resume		= venc_panel_resume,
 
 	.get_resolution	= omapdss_default_get_resolution,
+	.get_recommended_bpp = omapdss_default_get_recommended_bpp,
 
 	.driver         = {
 		.name   = "venc",