[IPV6]: Use macro for rwlock_t initialization.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index f829a4a..1cf305a 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -224,7 +224,7 @@
 
 	mc_lst->ifindex = dev->ifindex;
 	mc_lst->sfmode = MCAST_EXCLUDE;
-	mc_lst->sflock = RW_LOCK_UNLOCKED;
+	rwlock_init(&mc_lst->sflock);
 	mc_lst->sflist = NULL;
 
 	/*