power: supply: core: Add power_supply_battery_info and API

power_supply_get_battery_info() reads battery data from devicetree.
struct power_supply_battery_info provides battery data to drivers.
Its fields correspond to elements in enum power_supply_property.
Drivers may surface battery data in sysfs via corresponding
POWER_SUPPLY_PROP_* fields.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Liam Breck <kernel@networkimprov.net>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>