[SCSI] bnx2i: make firmware use statsn field when constructing header

instruct firmware to use driver/iscsid provided expected statsn field
while constructing login pdu header.

Initialize 'flags' to instruct chip to use driver/iscsid provided
ExpStatSN value while constructing iSCSI login PDU header

Signed-off-by: Eddie Wai <waie@broadcom.com>
Signed-off-by: Anil Veerabhadrappa <anilgv@broadcom.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>