can: sja1000: sja1000_err(): don't count arbitration lose as an error

Losing arbitration is normal in a CAN-bus network, it means that a higher
priority frame is being send and the pending message will be retried later.
Hence most driver only increment arbitration_lost, but the sja1000 driver also
incremeants tx_error, causing errors to be reported on a normal functioning
CAN-bus. So stop counting them as errors.

Fixes: 8935f57e ("can: sja1000: fix network statistics update")
Signed-off-by: Jeroen Hofstee <jhofstee@victronenergy.com>
Link: https://lore.kernel.org/r/20201127095941.21609-1-jhofstee@victronenergy.com


[mkl: split into two seperate patches]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>