can: bittiming: can_fixup_bittiming(): change type of tseg1 and alltseg to unsigned int

All timing calculation is done with unsigned integers, so change type
of tseg1 and alltseg to unsigned int, too.

Link: https://lore.kernel.org/all/20211013130653.1513627-1-mkl@pengutronix.de
Link: https://github.com/linux-can/can-utils/pull/314


Reported-by: Gary Bisson <bisson.gary@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>