[SCSI] lpfc 8.3.15: FCoE Related Fixes

FCoE Related Fixes
- Correct find-next-FCF routine so that it searches at next FCF rather
  than current one.
- Enhanced round-robin FCF failover algorithm to re-start on "New FCF"
  async event
- Update the manner in which we look at FCFs while they may be in
  their discovery state.
- Use LPFC_FCOE_NULL_VID macro when checkinf for valid vlan_id for FCF

Signed-off-by: Alex Iannicelli <alex.iannicelli@emulex.com>
Signed-off-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>