Bluetooth: 6lowpan: Fix imtu & omtu values

The omtu value is determined by the remote peer so there's no point in
trying to hard-code it to any value. The IPSP specification otoh gives
a more reasonable value for the imtu, i.e. 1280.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Acked-by: NJukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/bluetooth/6lowpan.c

@@ -775,8 +775,7 @@ static struct l2cap_chan *chan_create(void)
 
 	chan->chan_type = L2CAP_CHAN_CONN_ORIENTED;
 	chan->mode = L2CAP_MODE_LE_FLOWCTL;
-	chan->omtu = 65535;
-	chan->imtu = chan->omtu;
+	chan->imtu = 1280;
 
 	return chan;
 }