[SCSI] fcoe: support ndo_fcoe_ddp_target() for DDP in FCoE targe

Add ddp_target() support to the Open-FCoE sw fcoe hba driver (fcoe.ko).

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Kiran Patil <kiran.patil@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>