cc6kxbarFallbackMode controls system fallback to bus-mode
after loss of switching fabric module.
'true' - When the last fabric card is removed
system will adjust the supervisor and
line cards switching mode automatically without
resetting the system. With this feature enabled,
the switch might lose traffic while it's
changing the switching mode.
'false' - All the ports in the system will be
disabled when the last fabric card is removed.