PM / Domains: Validate cases of a non-bound driver in genpd governor

Recently genpd removed the requirement of a having a driver bound for its
attached devices to allow genpd to power off. That change should also have
removed a corresponding validation in the governor, let's correct that.

Fixes: 298cd0f08801 (PM / Domains: Remove dev->driver check for runtime)
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain_governor.c

@@ -160,9 +160,6 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
 		struct gpd_timing_data *td;
 		s64 constraint_ns;
 
-		if (!pdd->dev->driver)
-			continue;
-
 		/*
 		 * Check if the device is allowed to be off long enough for the
 		 * domain to turn off and on (that's how much time it will