PM / domains: Turn latency warning into debug message

If devices don't provide latency data, this warning can be quite noisy until
the pm domain was enabled and disabled a few times. Turn this warning into
a debug message.
Signed-off-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NUlf Hansson <ulf.hansson@linaro.org>
Acked-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -42,7 +42,7 @@
 	struct gpd_timing_data *__td = &dev_gpd_data(dev)->td;			\
 	if (!__retval && __elapsed > __td->field) {				\
 		__td->field = __elapsed;					\
-		dev_warn(dev, name " latency exceeded, new value %lld ns\n",	\
+		dev_dbg(dev, name " latency exceeded, new value %lld ns\n",	\
 			__elapsed);						\
 		genpd->max_off_time_changed = true;				\
 		__td->constraint_changed = true;				\