can: c_can: fix invalid error codes

commit 6ea45886865c1abb01bb861f7f6bdd5d0f398cb3 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>
Cc: Bhupesh Sharma <bhupesh.sharma@st.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>