net/ipv6: Fix misuse of proc_dointvec "skip_notify_on_dev_down"

/proc/sys/net/ipv6/route/skip_notify_on_dev_down assumes given value to be
0 or 1. Use proc_dointvec_minmax instead of proc_dointvec.

Fixes: 7c6bb7d2 ("net/ipv6: Add knob to skip DELROUTE message ondevice down")
Signed-off-by: NEiichi Tsukata <devel@etsukata.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -5281,7 +5281,7 @@ static struct ctl_table ipv6_route_table_template[] = {
 		.data		=	&init_net.ipv6.sysctl.skip_notify_on_dev_down,
 		.maxlen		=	sizeof(int),
 		.mode		=	0644,
-		.proc_handler	=	proc_dointvec,
+		.proc_handler	=	proc_dointvec_minmax,
 		.extra1		=	&zero,
 		.extra2		=	&one,
 	},