ieee802154 socket: Return EMSGSIZE from raw_sendmsg() if packet too big.

The proper return code for trying to send a packet that exceeds the
outgoing interface's MTU is EMSGSIZE, not EINVAL, so patch ieee802154's
raw_sendmsg() to do the right thing.  (Its dgram_sendmsg() was already
returning EMSGSIZE for this case.)
Signed-off-by: NLennert Buytenhek <buytenh@wantstofly.org>
Acked-by: NAlexander Aring <alex.aring@gmail.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/ieee802154/socket.c

@@ -284,7 +284,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 
 	if (size > mtu) {
 		pr_debug("size = %Zu, mtu = %u\n", size, mtu);
-		err = -EINVAL;
+		err = -EMSGSIZE;
 		goto out_dev;
 	}