power: supply: core: Fix parsing of battery chemistry/technology

The power_supply_get_battery_info() fails if device-chemistry property
is missing in a device-tree because error variable is propagated to the
final return of the function, fix it.

Fixes: 4eef766b ("power: supply: core: Parse battery chemistry/technology")
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/power_supply_core.c

@@ -619,8 +619,7 @@ int power_supply_get_battery_info(struct power_supply *psy,
 	 * Documentation/power/power_supply_class.rst.
 	 */
 
-	err = of_property_read_string(battery_np, "device-chemistry", &value);
-	if (!err) {
+	if (!of_property_read_string(battery_np, "device-chemistry", &value)) {
 		if (!strcmp("nickel-cadmium", value))
 			info->technology = POWER_SUPPLY_TECHNOLOGY_NiCd;
 		else if (!strcmp("nickel-metal-hydride", value))