can: gs_ubs: use KBUILD_MODNAME instead of hard coded names

The driver uses the string "gs_usb" to populate usb_driver::name,
can_bittiming_const::name and
can_data_bittiming_const::name. KBUILD_MODNAME evaluates to
"gs_ubs". Use KBUILD_MODNAME and get rid on the hardcoded string
names.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20220726082707.58758-7-mailhol.vincent@wanadoo.fr


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