[SCSI] fcoe: move packet handlers from fcoe_port to fcoe_interface

The packet handlers need to be tracked in fcoe_interface so there is only one
set per net_device.  When NPIV is enabled there will be multiple SCSI hosts
and multiple fcoe_port structures on a single net_device.

The packet handlers match by ethertype and netdev.  If the same handler gets
registered on a single netdev multiple times, the receive function will be
called multiple times for each frame.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>