can: mpc5xxx_can.c: Fix build failure

Fixes build error caused by the OF device_node pointer
being moved into struct device.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>