power: supply: cpcap-charger: Fix power_supply_put on null battery pointer

Currently if the pointer battery is null there is a null pointer
dereference on the call to power_supply_put.  Fix this by only
performing the put if battery is not null.

Addresses-Coverity: ("Dereference after null check")
Fixes: 4bff91bb ("power: supply: cpcap-charger: Fix missing power_supply_put()")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/cpcap-charger.c

@@ -300,8 +300,9 @@ cpcap_charger_get_bat_const_charge_voltage(struct cpcap_charger_ddata *ddata)
 				&prop);
 		if (!error)
 			voltage = prop.intval;
+
+		power_supply_put(battery);
 	}
-	power_supply_put(battery);
 
 	return voltage;
 }