VectorCAN: Fix receiving echo frames with CAN-FD

[ChangeLog][VectorCAN] Fixed that no echo frames
were received when both QCanBusDevice::CanFdKey
and QCanBusDevice::ReceiveOwnKey were set to true.

Fixes: QTBUG-145556
Pick-to: 6.11
Change-Id: I91c8869b7da42ece3bdb90299a507745b3d895c0
Reviewed-by: Stefan Steinwasser <stefan-qt@kcxh6.de>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: André Hartmann <aha_1980@gmx.de>