Clear the VendorVersion in the PLOGI/PLOGI ACC payload

Vendor version info may have been set on fabric login. Before sending
PLOGI payloads, ensure that it's cleared.
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>