can: peak_canfd: improves 32-bit alignment

The embedded firmware aligns its messages on 32-bit boundaries.
This patch makes sure to browse through the list of received messages
while respecting 32-bit alignment.

Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>