anycast: Some RCU conversions

- dev_get_by_flags() changed to dev_get_by_flags_rcu()

- ipv6_sock_ac_join() dont touch dev & idev refcounts
- ipv6_sock_ac_drop() dont touch dev & idev refcounts
- ipv6_sock_ac_close() dont touch dev & idev refcounts
- ipv6_dev_ac_dec() dount touch idev refcount
- ipv6_chk_acast_addr() dont touch idev refcount

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5156b80..c319f28 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1271,8 +1271,8 @@
 extern void		dev_remove_pack(struct packet_type *pt);
 extern void		__dev_remove_pack(struct packet_type *pt);
 
-extern struct net_device	*dev_get_by_flags(struct net *net, unsigned short flags,
-						  unsigned short mask);
+extern struct net_device	*dev_get_by_flags_rcu(struct net *net, unsigned short flags,
+						      unsigned short mask);
 extern struct net_device	*dev_get_by_name(struct net *net, const char *name);
 extern struct net_device	*dev_get_by_name_rcu(struct net *net, const char *name);
 extern struct net_device	*__dev_get_by_name(struct net *net, const char *name);