thermal: Do not log an error if thermal_zone_get_temp returns -EAGAIN

Some temperature sensors only get updated every few seconds and while
waiting for the first irq reporting a (new) temperature to happen there
get_temp operand will return -EAGAIN as it does not have any data to report
yet.

Not logging an error in this case avoids messages like these from showing
up in dmesg on affected systems:

[    1.219353] thermal thermal_zone0: failed to read out thermal zone 0
[    2.015433] thermal thermal_zone0: failed to read out thermal zone 0
[    2.416737] thermal thermal_zone0: failed to read out thermal zone 0
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/thermal_core.c

@@ -458,8 +458,10 @@ static void update_temperature(struct thermal_zone_device *tz)
 
 	ret = thermal_zone_get_temp(tz, &temp);
 	if (ret) {
-		dev_warn(&tz->device, "failed to read out thermal zone %d\n",
-			 tz->id);
+		if (ret != -EAGAIN)
+			dev_warn(&tz->device,
+				 "failed to read out thermal zone (%d)\n",
+				 ret);
 		return;
 	}