power: supply: bq25890: show max charge current/voltage as configured

Use firmware-provided limits for POWER_SUPPLY_*_MAX properties instead
of chip max values. This will reflect the battery limits as those are
the important ones.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>