[SCSI] zfcp: Fix logic for physical port close

After closing the port, we want it to be "not open" to consider the
action to be successful.

Reviewed-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>