[IPV6] ADDRCONF: Fix conflicts in DEVCONF_xxx constant.

Signed-off-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/ipv6.h

@@ -209,9 +209,8 @@ enum {
 	DEVCONF_RTR_PROBE_INTERVAL,
 	DEVCONF_ACCEPT_RA_RT_INFO_MAX_PLEN,
 	DEVCONF_PROXY_NDP,
-	__DEVCONF_OPTIMISTIC_DAD,
-	DEVCONF_ACCEPT_SOURCE_ROUTE,
 	DEVCONF_OPTIMISTIC_DAD,
+	DEVCONF_ACCEPT_SOURCE_ROUTE,
 	DEVCONF_MAX
 };