can: pch_can: fix invalid error codes

commit ee50e135aeb048b90fab662e661c58b67341830b upstream.

Errors in CAN protocol (location) are reported in data[3] of the can
frame instead of data[2].

Signed-off-by: Olivier Sobrie <olivier@sobrie.be>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>