can: gs_usb: add extended bt_const feature

For example CANext FD needs to distinguish between bittiming constants
valid for arbitration phase and data phase to reach maximum
performance at higher speeds.

Link: https://lore.kernel.org/all/20220309124132.291861-20-mkl@pengutronix.de
Signed-off-by: Peter Fink <pfink@christ-es.de>
Signed-off-by: Christoph Möhring <cmoehring@christ-es.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>