can: sja1000: do not report txerr and rxerr during bus-off

[ Upstream commit 164d7cb2d5a30f1b3a5ab4fab1a27731fb1494a8 ]

During bus off, the error count is greater than 255 and can not fit in
a u8.

Fixes: 215db185 ("can: sja1000: Consolidate and unify state change handling")
Link: https://lore.kernel.org/all/20220719143550.3681-4-mailhol.vincent@wanadoo.fr


Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>