Bluetooth: Use const for struct l2cap_ops field

The struct l2cap_ops field should not allow any modifications and thus
it is better declared as const.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

include/net/bluetooth/l2cap.h

@@ -579,7 +579,7 @@ struct l2cap_chan {
 	struct list_head	global_l;
 
 	void			*data;
-	struct l2cap_ops	*ops;
+	const struct l2cap_ops	*ops;
 	struct mutex		lock;
 };