pm8001: more fixes to honor return value

The driver ignores the return value in a lot of places, fix
it at least somewhere (and release the resources in such cases),
to avoid that bad things happen.
A memory leak is fixed too.

Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Acked-by: Suresh Thiagarajan <Suresh.Thiagarajan@pmcs.com>
Acked-by: Jack Wang <xjtuwjp@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>