power: supply: smb347-charger: Use generic property framework

Simplify the driver and remove the DT specific code by
using the generic device property framework.

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>