On host shutdown, driver sends 'SMA_Disabled' as a reason
for link down. This is incorrect.

Send 'reboot' as a linkdown reason.
Signed-off-by: NJan Sokolowski <jan.sokolowski@intel.com>
Reviewed-by: NJakub Byczkowski <jakub.byczkowski@intel.com>
Signed-off-by: NDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>