OPP: Rename and relocate of_genpd_opp_to_performance_state()

The OPP core already has the performance state values for each of the
genpd's OPPs and there is no need to call the genpd callback again to
get the performance state for the case where the end device doesn't have
an OPP table and has the "required-opps" property directly in its node.

This commit renames of_genpd_opp_to_performance_state() as
of_get_required_opp_performance_state() and moves it to the OPP core, as
it is all about OPP stuff now.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/base/power/domain.c

@@ -2552,54 +2552,6 @@ unsigned int pm_genpd_opp_to_performance_state(struct device *genpd_dev,
 }
 EXPORT_SYMBOL_GPL(pm_genpd_opp_to_performance_state);
 
-/**
- * of_genpd_opp_to_performance_state- Gets performance state of device's
- * power domain corresponding to a DT node's "required-opps" property.
- *
- * @dev: Device for which the performance-state needs to be found.
- * @np: DT node where the "required-opps" property is present. This can be
- *	the device node itself (if it doesn't have an OPP table) or a node
- *	within the OPP table of a device (if device has an OPP table).
- *
- * Returns performance state corresponding to the "required-opps" property of
- * a DT node. This calls platform specific genpd->opp_to_performance_state()
- * callback to translate power domain OPP to performance state.
- *
- * Returns performance state on success and 0 on failure.
- */
-unsigned int of_genpd_opp_to_performance_state(struct device *dev,
-					       struct device_node *np)
-{
-	struct generic_pm_domain *genpd;
-	struct dev_pm_opp *opp;
-	int state = 0;
-
-	genpd = dev_to_genpd(dev);
-	if (IS_ERR(genpd))
-		return 0;
-
-	if (unlikely(!genpd->set_performance_state))
-		return 0;
-
-	genpd_lock(genpd);
-
-	opp = of_dev_pm_opp_find_required_opp(&genpd->dev, np);
-	if (IS_ERR(opp)) {
-		dev_err(dev, "Failed to find required OPP: %ld\n",
-			PTR_ERR(opp));
-		goto unlock;
-	}
-
-	state = genpd->opp_to_performance_state(genpd, opp);
-	dev_pm_opp_put(opp);
-
-unlock:
-	genpd_unlock(genpd);
-
-	return state;
-}
-EXPORT_SYMBOL_GPL(of_genpd_opp_to_performance_state);
-
 static int __init genpd_bus_init(void)
 {
 	return bus_register(&genpd_bus_type);