PM / OPP: remove double calls to find_device_opp()

By mistake we called find_device_opp() twice in of_free_opp_table(), fix it.

Generated diff doesn't show the problem well and so here is the code snippet:

void of_free_opp_table(struct device *dev)
{
	struct device_opp *dev_opp = find_device_opp(dev);
	struct dev_pm_opp *opp, *tmp;

	/* Check for existing list for 'dev' */
	dev_opp = find_device_opp(dev);

	...
}
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/opp.c

@@ -768,7 +768,7 @@ EXPORT_SYMBOL_GPL(of_init_opp_table);
  */
 void of_free_opp_table(struct device *dev)
 {
-	struct device_opp *dev_opp = find_device_opp(dev);
+	struct device_opp *dev_opp;
 	struct dev_pm_opp *opp, *tmp;
 
 	/* Check for existing list for 'dev' */