net: remove dev_base_lock from do_setlink()

We hold RTNL here, and dev->link_mode readers already
are using READ_ONCE().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -2961,11 +2961,9 @@ static int do_setlink(const struct sk_buff *skb,
 	if (tb[IFLA_LINKMODE]) {
 		unsigned char value = nla_get_u8(tb[IFLA_LINKMODE]);
 
-		write_lock(&dev_base_lock);
 		if (dev->link_mode ^ value)
 			status |= DO_SETLINK_NOTIFY;
 		WRITE_ONCE(dev->link_mode, value);
-		write_unlock(&dev_base_lock);
 	}
 
 	if (tb[IFLA_VFINFO_LIST]) {