[SCSI] zfcp: Use correct length for FCP_RSP_INFO

Use the FCP_RSP_INFO length to correctly skip the FCP_RSP_INFO field.

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>