power: supply: rt9467: Make charger-enable control as logic level

The current coding make 'charger-enable-gpio' control as real hardware
level. This conflicts with the default binding example. For driver
behavior, no need to use real hardware level, just logic level is
enough. This change can make this flexibility keep in dts gpio active
level about this pin.

Fixes: 6f7f70e3 ("power: supply: rt9467: Add Richtek RT9467 charger driver")
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>