[SCSI] fcoe: add check to fail gracefully in bonding mode

This patch adds a check to fail gracefully when the netdevice
is bonded.  Previously, the error was detected but the stack
would continue to load.  This resulted in a partially enabled
fcoe intance and errors when the fcoe instance was destroy.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>