Adding support for charge properties for gas gauge.

Also ensuring that battery mode is correct now for energy as well as
charge properties by setting it on the fly.

I also added 2 functions to power_supply.h to help identify the units for
specific properties more easily by power supplies.
Signed-off-by: NRhyland Klein <rklein@nvidia.com>
Signed-off-by: NAnton Vorontsov <cbouatmailru@gmail.com>

This patch adds properties to support devicekit power. Also, create IO
wrapper functions and fix some issues found while testing, including
unit conversions to match the power_supply types.
Signed-off-by: NRhyland Klein <rklein@nvidia.com>
Signed-off-by: NAnton Vorontsov <cbouatmailru@gmail.com>

This driver depends on I2C and uses SMBUS for communication with
the host.
Signed-off-by: NRhyland Klein <rklein@nvidia.com>
Reviewed-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Reviewed-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NAnton Vorontsov <cbouatmailru@gmail.com>