power: bq25890: update state on property read

Edge interrupts from the charger may be lost or stuck in fault mode
since probe(). Check if something changed everytime userspace wants
some data.

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