power: supply: add battery parameters

Add parsing of new device-tree battery bindings.

     - trickle-charge-current-microamp
     - precharge-upper-limit-microvolt
     - re-charge-voltage-microvolt
     - over-voltage-threshold-microvolt

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>