Bluetooth: Remove magic value in disconnect mgmt handler

This patch replaces the magic value of variable 'reason' by the
proper macro.
Signed-off-by: NAndre Guedes <andre.guedes@openbossa.org>
Signed-off-by: NGustavo Padovan <gustavo.padovan@collabora.co.uk>

net/bluetooth/mgmt.c

@@ -1611,7 +1611,7 @@ static int disconnect(struct sock *sk, struct hci_dev *hdev, void *data,
 	}
 
 	dc.handle = cpu_to_le16(conn->handle);
-	dc.reason = 0x13; /* Remote User Terminated Connection */
+	dc.reason = HCI_ERROR_REMOTE_USER_TERM;
 
 	err = hci_send_cmd(hdev, HCI_OP_DISCONNECT, sizeof(dc), &dc);
 	if (err < 0)