nl80211: call cfg80211_dev_rename() under RTNL

This is required, and we have an assertion, move the RTNL
unlock down to cover cfg80211_dev_rename().

Fixes: a05829a ("cfg80211: avoid holding the RTNL when calling the driver")
Reported-by: syzbot+ed107c5fa3e21cdcd86e@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20210128183454.16a4ea036740.I2beeb391dc322d6f1df3ee2612e714e0a7817397@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -3220,7 +3220,6 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 		wdev = netdev->ieee80211_ptr;
 
 	wiphy_lock(&rdev->wiphy);
-	rtnl_unlock();
 
 	/*
 	 * end workaround code, by now the rdev is available
@@ -3230,6 +3229,7 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 	if (info->attrs[NL80211_ATTR_WIPHY_NAME])
 		result = cfg80211_dev_rename(
 			rdev, nla_data(info->attrs[NL80211_ATTR_WIPHY_NAME]));
+	rtnl_unlock();
 
 	if (result)
 		goto out;