cpufreq: dt: Drop stale comment

The comment in file header doesn't hold true anymore, drop it.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq-dt.c

@@ -4,9 +4,6 @@
  * Copyright (C) 2014 Linaro.
  * Viresh Kumar <viresh.kumar@linaro.org>
  *
- * The OPP code in function set_target() is reused from
- * drivers/cpufreq/omap-cpufreq.c
- *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.