selftests: fib_tests: sleep after changing carrier

sleep for a second after setting carrier down to allow linkwatch
to propagate the change to the routing stack via netdev_state_change.
As it stands there is a race setting carrier down on the dummy
device and then checking the linkdown flag in the routes.
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/net/fib_tests.sh

@@ -282,6 +282,7 @@ fib_carrier_local_test()
 
 	set -e
 	ip -netns testns link set dev dummy0 carrier off
+	sleep 1
 	set +e
 
 	echo "    Carrier off on nexthop"