power: supply: charger-manager: fix incorrect check on charging_duration_ms

Currently the duration check on the discharging duration setting is
checking the charging duration rather than the discharging duration
due to a cut-n-paste coding error. Fix this by checking the value
desc->charging_max_duration_ms.

Addresses-Coverity: ("Copy-paste-error")
Fixes: 8fcfe088 ("charger-manager: Support limit of maximum possible")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/charger-manager.c

@@ -471,7 +471,7 @@ static int check_charging_duration(struct charger_manager *cm)
 	} else if (cm->battery_status == POWER_SUPPLY_STATUS_NOT_CHARGING) {
 		duration = curr - cm->charging_end_time;
 
-		if (duration > desc->charging_max_duration_ms) {
+		if (duration > desc->discharging_max_duration_ms) {
 			dev_info(cm->dev, "Discharging duration exceed %ums\n",
 				 desc->discharging_max_duration_ms);
 			ret = true;