We introduced some new locking here, but need to update the error
paths so they unlock before returning.

Fixes: 72d9cd9c ("power: bq25890: protect view of the chip's state")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>