[SCSI] zfcp: Implicitly close all wka ports

An adapter shutdown implicitly closes all open ports. Make sure to
mark all WKA ports as offline, not only the directory server. Also
make sure that no pending wka port work is running when the adapter is
being removed.

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@suse.de>