bq24190_charger: Add support for TI BQ24190 Battery Charger

Add driver support for the Texas Instruments BQ24190 battery charger.
Some of the information provided by the device is about the charger and
other information is about the battery so create two power_supply objects
(one for each) and provide the appropriate information for each one.

The device has many fields that go beyond what is reasonable to report or
modify using the existing 'POWER_SUPPLY_PROP_*' properties so the driver
exports the register fields via sysfs.  They are prefixed by 'f_' (for
'field') to make it easier to distinguish between a register field and a
"normal" sysfs file exported by the power_supply infrastructure.

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>