[SCSI] zfcp: incorrect reaction on incoming RSCN

After an error condition resolved a remote storage port was never
re-opened. The incoming RSCN was not processed accordingly due
to a misinterpreted status flag / return value combination.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>