ARM: OMAP3+: do not register non-dt OPP tables for device tree boot

OMAP3+ supports both device tree and non-device tree boot.
Device tree bindings for OMAP3+ is supposed to be added via dts following:
Documentation/devicetree/bindings/power/opp.txt

Since we now have device tree entries for OMAP3+ cpu OPPs,
The current code wrongly adds duplicate OPPs. So, dont register OPPs
when booting using device tree.
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/opp.c

@@ -17,6 +17,7 @@
  * GNU General Public License for more details.
  */
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/opp.h>
 #include <linux/cpu.h>
 
@@ -40,6 +41,9 @@ int __init omap_init_opp_table(struct omap_opp_def *opp_def,
 {
 	int i, r;
 
+	if (of_have_populated_dt())
+		return -EINVAL;
+
 	if (!opp_def || !opp_def_size) {
 		pr_err("%s: invalid params!\n", __func__);
 		return -EINVAL;