scsi: lpfc: Fix sysfs Speed value on CNA ports

CNA ports were showing speed as "unknown" even if the link is up.

Add speed decoding for FCOE-based adapters.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>