[SCSI] zfcp: Use correct req_id for traces

The zfcp traces used the fsf_req address in place of the req_id.
Change this to save the correct req_id.

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>