power_supply: Add support for bq24735 charger

Adds support for the bq24735 charger chipset. The bq24735 is a
high-efficiency, synchronous battery charger.

It allows control of the charging current, input current, and the charger
voltage DAC's through SMBus.

Signed-off-by: Darbha Sriharsha <dsriharsha@nvidia.com>
Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Thanks-to: Stephen Warren <swarren@wwwdotorg.org>
Thanks-to: Thierry Reding <thierry.reding@gmail.com>
Thanks-to: Manish Badarkhe <badarkhe.manish@gmail.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>