From: Sven Eckelmann <sven@narfation.org>
Date: Thu, 23 May 2019 19:26:36 +0200
Subject: Revert "batman-adv: compat: Drop support for genl_ops->start"

OpenWrt's mac80211 package is not yet ready to support the generic netlink
API of Linux 5.2.

This reverts commit 1d30dbe3917d0d6fdb8ba473dfdd6265ac46670b.

--- a/compat-include/net/genetlink.h
+++ b/compat-include/net/genetlink.h
@@ -42,6 +42,7 @@ enum genl_validate_flags {
 struct batadv_genl_ops {
 	int		       (*doit)(struct sk_buff *skb,
 				       struct genl_info *info);
+	int		       (*start)(struct netlink_callback *cb);
 	int		       (*dumpit)(struct sk_buff *skb,
 					 struct netlink_callback *cb);
 	int		       (*done)(struct netlink_callback *cb);
@@ -104,6 +105,7 @@ static inline int batadv_genl_register_f
 
 	for (i = 0; i < family->family.n_ops; i++) {
 		ops[i].doit = family->ops[i].doit;
+		ops[i].start = family->ops[i].start;
 		ops[i].dumpit = family->ops[i].dumpit;
 		ops[i].done = family->ops[i].done;
 		ops[i].cmd = family->ops[i].cmd;