PM: domains: Fix domain attach for CONFIG_PM_OPP=n

If CONFIG_PM_OPP=n, of_get_required_opp_performance_state() always
returns -EOPNOTSUPP, and all drivers for devices that are part of a PM
Domain fail to probe with:

    failed to set required performance state for power-domain foo: -95
    probe of bar failed with error -95

Fix this by treating -EOPNOTSUPP the same as -ENODEV.

Fixes: c016baf7 ("PM: domains: Add support for 'required-opps' to set default perf state")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -2689,7 +2689,7 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
 
 	/* Set the default performance state */
 	pstate = of_get_required_opp_performance_state(dev->of_node, index);
-	if (pstate < 0 && pstate != -ENODEV) {
+	if (pstate < 0 && pstate != -ENODEV && pstate != -EOPNOTSUPP) {
 		ret = pstate;
 		goto err;
 	} else if (pstate > 0) {