can: kvaser_pciefd: Add intermediate variable for device struct in probe()

Add intermediate variable, for readability and to simplify future patches.

Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Link: https://patch.msgid.link/20250725123230.8-4-extja@kvaser.com


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