[SCSI] libfcoe: add implementation to support fcoe transport

Add the new fcoe_transport.c file that implements basic fcoe transport
interface. Eventually, the sysfs entries to create/destroy/enable/disable
an FCoE instance will be coming to the fcoe transport layer, who does a
look-up to find the corresponding transport provide and pass the corresponding
action over to the identified provider.

The fcoe.ko will become the default fcoe transport provider that can support
FCoE on any given netdev interfaces, as the Open-FCoE.org's default software
FCoE HBA solution. Any vendor specific FCoE HBA driver that is built on top
of Open-FCoE's kernel stack of libfc & libfcoe as well as the user land tool
of fcoe-utils can easily plug-in and start running FCoE on their network
interfaces. The fcoe.ko will be converted to act as the default provider if
no vendor specific transport provider is found, as it is always added to the
very end of the list of attached transports.

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Bhanu Prakash Gollapudi <bprakash@broadcom.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>