PM / devfreq: Remove duplicate include of opp.h

Currently, code include opp.h twice. Remove one inclusion
of opp.h

Signed-off-by: Manish Badarkhe <badarkhe.manish@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/devfreq/exynos/exynos5_bus.c

@@ -18,7 +18,6 @@
 #include <linux/opp.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
-#include <linux/opp.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/platform_device.h>