[SCSI] fcoe: add support to FCoE offload support in fcoe_sw through net_device

This adds implementation of ddp_setup()/ddp_done() in fcoe_sw for its
fcoe_sw_libfc_fcn_templ.

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