[IPV6]: ROUTE: Add router_probe_interval sysctl.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 108b75d..c609cc7 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -149,6 +149,7 @@
 	__s32		accept_ra_pinfo;
 #ifdef CONFIG_IPV6_ROUTER_PREF
 	__s32		accept_ra_rtr_pref;
+	__s32		rtr_probe_interval;
 #endif
 	void		*sysctl;
 };
@@ -175,6 +176,7 @@
 	DEVCONF_ACCEPT_RA_DEFRTR,
 	DEVCONF_ACCEPT_RA_PINFO,
 	DEVCONF_ACCEPT_RA_RTR_PREF,
+	DEVCONF_RTR_PROBE_INTERVAL,
 	DEVCONF_MAX
 };