can: gs_usb: gs_usb_set_timestamp(): remove return statements form void function

Remove the return statements from void gs_usb_set_timestamp()
function, as it's not generally useful.

Link: https://lore.kernel.org/all/20230718-gs_usb-cleanups-v1-3-c3b9154ec605@pengutronix.de


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>