After commit ebc0ffae (RCU conversion of fib_lookup()),
fib_result_assign()  should not change fib refcounts anymore.

Thanks to Michael who did the bisection and bug report.
Reported-by: NMichael Ellerman <michael@ellerman.id.au>
Tested-by: NMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>