power: max14577: Remove SYSFS dependency from Kconfig

This is only a small clean-up. The driver can be built without SYSFS
as there exist stubs for used functions.

Signed-off-by: Karol Wrona <k.wrona@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>