fcoe: use enum for fip_mode

The FIP mode is independent on the FIP state machine, so use a separate
enum for that instead of overloading it with state machine values.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Acked-by: Johannes Thumshirn <jth@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>