can: peak_pci: fix checkpatch warnings

This patch cleans several checkpatch warnings in the peak_pci driver.

Cc: Stephane Grosjean <s.grosjean@peak-system.com>
Link: https://lore.kernel.org/r/20210616102811.2449426-0-mkl@pengutronix.de


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