power: supply: bq27xxx: support missing supplier device

power_supply_am_i_supplied() can return negative error
codes. In this case we should assume, that no charger
is connected and the battery should be marked as
DISCHARGING instead of NOT_CHARGING.

Reported-by: Merlijn Wajer <merlijn@wizzup.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

drivers/power/supply/bq27xxx_battery.c

@@ -1670,7 +1670,7 @@ static int bq27xxx_battery_status(struct bq27xxx_device_info *di,
 			status = POWER_SUPPLY_STATUS_FULL;
 		else if (di->cache.flags & BQ27000_FLAG_CHGS)
 			status = POWER_SUPPLY_STATUS_CHARGING;
-		else if (power_supply_am_i_supplied(di->bat))
+		else if (power_supply_am_i_supplied(di->bat) > 0)
 			status = POWER_SUPPLY_STATUS_NOT_CHARGING;
 		else
 			status = POWER_SUPPLY_STATUS_DISCHARGING;