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>