Bluetooth: ath3k: fix checkpatch warning

This patch fixed warning:
 WARNING: Prefer using '"%s...", __func__' to using 'ath3k_disconnect', this function's name, in a string
 #568: FILE: drivers/bluetooth/ath3k.c:568:
 +	BT_DBG("ath3k_disconnect intf %p", intf);
Signed-off-by: Maxim Zhukov <mussitantesmortem@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/ath3k.c

@@ -569,7 +569,7 @@ static int ath3k_probe(struct usb_interface *intf,
 
 static void ath3k_disconnect(struct usb_interface *intf)
 {
-	BT_DBG("ath3k_disconnect intf %p", intf);
+	BT_DBG("%s intf %p", __func__, intf);
 }
 
 static struct usb_driver ath3k_driver = {