[SCSI] zfcp: Remove duplicate assignment of req_seq_no

zfcp_fsf_req_create assigns the same value twice to req_seq_no.
Remove one assignment and move the req_id and seq_no assignments to
one place.

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>