can: softing: remove redundant NULL check

In this case dev cannot be NULL, so remove redundant check.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 03fd3cf5 ("can: add driver for Softing card")
Signed-off-by: Daniil Dulov <d.dulov@aladdin.ru>
Link: https://lore.kernel.org/all/20240211150535.3529-1-d.dulov@aladdin.ru


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