power: supply: max17040: remove unneeded double cast

There is no need for double explicit cast from of_device_get_match_data()
(uintptr_t and then to target enum) because implicit conversion from
uintptr_t to enum is straightforward (uintptr_t is a integer type).

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>