Bluetooth: fix crash with quirky dongles doing sound

Quirky dongles sometimes do not use the iso interface which
causes a crash with runtime PM

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

drivers/bluetooth/btusb.c

@@ -829,7 +829,7 @@ static void btusb_work(struct work_struct *work)
 
 	if (hdev->conn_hash.sco_num > 0) {
 		if (!test_bit(BTUSB_DID_ISO_RESUME, &data->flags)) {
-			err = usb_autopm_get_interface(data->isoc);
+			err = usb_autopm_get_interface(data->isoc ? data->isoc : data->intf);
 			if (err < 0) {
 				clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
 				usb_kill_anchored_urbs(&data->isoc_anchor);
@@ -858,7 +858,7 @@ static void btusb_work(struct work_struct *work)
 
 		__set_isoc_interface(hdev, 0);
 		if (test_and_clear_bit(BTUSB_DID_ISO_RESUME, &data->flags))
-			usb_autopm_put_interface(data->isoc);
+			usb_autopm_put_interface(data->isoc ? data->isoc : data->intf);
 	}
 }