fib: fib_rules_cleanup can be static

fib_rules_cleanup_ups is only defined and used in one place.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>