power: supply: smb347-charger: Remove virtual smb347-battery

SMB347 is a charger and not a battery driver. Secondly, power-supply core
now supports monitored-battery. So the 'fake' battery doesn't do anything
useful for us, and thus, it should be removed.

Transfer smb347-battery functionality into smb347-mains and smb347-usb.

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>