ipv6/route: return if there is no fib_nh_gw_family

Previously we will return directly if (!rt || !rt->fib6_nh.fib_nh_gw_family)
in function rt6_probe(), but after commit cc3a86c8
("ipv6: Change rt6_probe to take a fib6_nh"), the logic changed to
return if there is fib_nh_gw_family.

Fixes: cc3a86c8 ("ipv6: Change rt6_probe to take a fib6_nh")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -634,7 +634,7 @@ static void rt6_probe(struct fib6_nh *fib6_nh)
 	 * Router Reachability Probe MUST be rate-limited
 	 * to no more than one per minute.
 	 */
-	if (fib6_nh->fib_nh_gw_family)
+	if (!fib6_nh->fib_nh_gw_family)
 		return;
 
 	nh_gw = &fib6_nh->fib_nh_gw6;