power: supply: max17040: Send uevent in SOC and status change

Notify core through power_supply_changed() in case of changes in state
of charge and power supply status. This is useful for user-space to
efficiently update current battery level.

Signed-off-by: Matheus Castello <matheus@castello.eng.br>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>