[SCSI] libfc: use lso_max for sequence offload

Make sure for large send is supported by LLD in outgoing FCP data, we are only
sending the lso_max a time in one single large send, since that is what
supported by LLD.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>