can: sja1000: plx_pci: Add support for Moxa CAN devices

This patch adds support for Moxa CAN devices.

Signed-off-by: Lukas Resch <l.resch@incubedit.com>
Signed-off-by: Christoph Zehentner <c.zehentner@incubedit.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>