power: supply: sbs-battery: Add TI BQ20Z65 support

Add support for BQ20Z65 manufacturer data to the sbs-battery
driver. Implementation has been verified using the public TRM
available from [0] and tested using a GE Flex 3S2P battery.

[0] http://www.ti.com/lit/pdf/sluu386



Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>