Bluetooth: Create debugfs directory for each connection handle

For every internal representation of a Bluetooth connection which is
identified by hci_conn, create a debugfs directory with the handle
number as directory name.

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

include/net/bluetooth/hci_core.h

@@ -440,6 +440,7 @@ struct hci_conn {
 	struct delayed_work le_conn_timeout;
 
 	struct device	dev;
+	struct dentry	*debugfs;
 
 	struct hci_dev	*hdev;
 	void		*l2cap_data;