OMAPDSS: FEATURES: Create a range param to get max downscaling

Create a dss_range_param member called FEAT_PARAM_DOWNSCALE to get the maximum
downscaling possible on the current platform. Use this in
dispc_ovl_calc_scaling().

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dispc.c b/drivers/video/omap2/dss/dispc.c
index 68a11e3..5e6849e 100644
--- a/drivers/video/omap2/dss/dispc.c
+++ b/drivers/video/omap2/dss/dispc.c
@@ -1692,7 +1692,7 @@
 		enum omap_color_mode color_mode, bool *five_taps)
 {
 	struct omap_overlay *ovl = omap_dss_get_overlay(plane);
-	const int maxdownscale = cpu_is_omap34xx() ? 4 : 2;
+	const int maxdownscale = dss_feat_get_param_max(FEAT_PARAM_DOWNSCALE);
 	unsigned long fclk = 0;
 
 	if ((ovl->caps & OMAP_DSS_OVL_CAP_SCALE) == 0) {