can: fix assignment of error location in CAN error messages

As Dan Carpenter reported in http://marc.info/?l=linux-can&m=144793696016187


the assignment of the error location in CAN error messages had some bit wise
overlaps. Indeed the value to be assigned in data[3] is no bitfield but defines
a single value which points to a location inside the CAN frame on the wire.

This patch fixes the assignments for the error locations in error messages.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>